Autumn Root Vegetable Gratin with Herbs and Cheese

September 30, 2014

Test Kitchen-Approved

Author Notes: I don't know many people who would turn down a potato gratin, do you? What I love about this classic dish, other than its near universal appeal, is that it is deceptively simple to make relative to its beauty. Plus, you can probably make it with what you have in your fridge and pantry right now.

My go-to gratin is the one I learned in cooking school; it relies on garlic-infused milk instead of cream, and the potatoes are thinly sliced and added to the baking dish raw. (I find par-boiled gratins are often grainy and/or mushy, and you can't layer the potatoes into the dish in as pretty and precise a pattern if you've already cooked them.) Other than the garlic, for flavor all you add is salt, pepper, and some Gruyère cheese -- that's it. You bake the gratin in a hot oven until the potatoes are tender and the milk thickens into a sauce, and you've got a gorgeous, versatile side dish.

After having relied on my old standard for over 15 years (yikes!), I decided to shake things up a bit. With all the lovely roots and tubers appearing in the markets, why not apply the same technique to a mix of vegetables? And maybe I could even throw in some herbs and switch up the cheese while I was at it.
Merrill Stubbs

Serves: 6


  • 1 1/2 cups whole milk
  • 2 cloves garlic
  • Pinch freshly grated nutmeg
  • 2 tablespoons extra virgin olive oil
  • 3/4 pound butternut squash
  • 3/4 pound white potatoes
  • 1/2 pound parsnips
  • Salt and pepper
  • 1/4 teaspoon chopped fresh thyme leaves
  • 1/4 teaspoon finely chopped fresh rosemary
  • 1 cup grated Gruyère
  • 1 cup grated Pecorino
In This Recipe


  1. Heat the oven to 400° F. Put the milk in a small heavy saucepan and peel and smash one of the garlic cloves. Add it to the milk and then heat the milk over low heat until it just starts to bubble at the edges. Remove from the heat, add the nutmeg and let steep while you continue with the recipe.
  2. Peel the second garlic clove, cut it in half and rub the cut side around the inside of a 6-cup baking dish no more than 2 inches deep. Rub 1 tablespoon of the oil all over the inside of the dish.
  3. Peel the squash, potatoes and parsnips and cut them into very thin slices (1/8-inch thick). If you have a mandoline, now's the time to use it.
  4. Layer the vegetables into the baking dish, alternating between squash, potato and parsnip, and fanning them into concentric, overlapping circles. Season generously with salt and pepper and sprinkle a third of the cheese and a third of the chopped herbs over the slices. Repeat twice, making the top layer as neat and tidy as you can.
  5. Remove the garlic clove from the hot milk and pour the milk evenly over the vegetables. Drizzle the remaining olive oil over the top of the gratin and bake for about 50 minutes, until the top is browned and bubbly and the vegetables yield easily when you poke them with a sharp knife. If the vegetables are tender but the top isn't as brown as you'd like, turn on the broiler for a couple of minutes -- watch it carefully so it doesn't burn! Let the gratin cool for at least 5 minutes before serving.

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Reviews (70) Questions (1)

70 Reviews

Footnotes November 11, 2017
I'm so excited to try this! I love playing with roots in new ways. Question... is the original recipe that Merrill mentions (potato gratin) the essentially the same save the roots?
gillianknitsalot September 30, 2017
So delicious, but mine separated as well. So, not pretty but very tasty.
judy November 5, 2016
I often have a problem with broken sauce is recipes like these. I wonder if a spoonful of flour thrown into the milk would work? Or perhaps make a slurry then add?
glammie December 31, 2015
I don't have an answer about the liquid, but I've found that if I cook a gratin at 324 (a nice slow oven) the cheese doesn't seize.
SallyF December 2, 2015
PS, I re-read and noted several comments re excessive liquid after baking. I stated that I did not have any extra juicy liquid in my casserole. I am now wondering if, by baking out ahead of time, the vegs may have soaked up any juices? I guess I'll never know!
SallyF December 2, 2015
I have been saving this recipe for a couple weeks, decided to "make/test run it" yesterday for husband and I. The slicing prep is a bit labor intensive, but the final result is OH SO WORTH IT! I actually made it late morning and we didn't eat it until dinner. After baking (mine was done in 45 min.), I covered the casserole with a lightly sprayed EVOO piece of foil, held it aside, and for dinner sliced pie shaped slices and reheated them (covered) in the microwave. OH SO GOOD!! The flavor is excellent! I wish the casserole was a little thicker (because I wanted more!) But the slices were pretty on the plates. I am testing further to see how the leftovers will freeze, then reheat. I had no problem with curdling or watery juice collecting from the vegs, even after sitting for several hours. The only change I made was to add 2 cups of milk because my bottle was a small 2 c. bottle so I decided to use it all. Don't deviate from the rest of the ingredients - the Gruyere and Pecorino impart a wonderful flavor to the 3 vegs. I wish slicing was easier, that took the longest. Make sure the squash has a long enough neck to keep slices solid and round. I was lucky enough to find a huge parsnip at the market. I will definitely make this again but next time will test by assembling all ahead of time, then bake out 45 min before dinner is ready. In that case, that little extra milk might help being added right before baking? Bottom line, EXCELLENT GRATIN!
John December 1, 2015
What a beautiful picture. It look so delicious this recipe I can't wait to make it.
Laura415 November 14, 2015
I will make this but I will use this method of making a gratin,<br /><br />Essentially you cook your sliced root veggies in the milk mixture until they are tender but not done. Then layer in dish with cheese etc and bake until the cheese is melted. The starch from the potatoes comes out into the milk and the veggies are mostly cooked so no watery mess of curdled milk and separated cheese.
Emily November 14, 2015
Can the time/temp be adjusted? I want to pop it in alongside my turkey towards the end, which is cooking at 325.
GH November 10, 2015
I thought it wouldn't happen to me, but it did. A watery mess and curdled cheese. I substituted yellow beets for the potatoes, so maybe that eliminated some starch to thicken it. I used almond milk but aside from that I followed the recipe exactly. In the past I have always used cream and covered the gratin, uncovering it only to brown the top. I also thought it would thicken upon standing but no luck.
Danielle November 4, 2015
I made this the other night and unfortunately, didn't have great results. I'm wondering if you could give me some insight as to why, since I loved the flavors and would love to try to make it again. I guess my biggest concern was that all of the cheese seemed to slide down to the edges of the dish once I poured the milk over it. Then the cheese took on a curdled look instead of gooey and cheesy. I also felt like the potatoes released water while cooking, which added a bit too much liquid to my dish. Like I said before, the flavors were still there and wonderful - I've actually been eating the leftovers with my eggs every morning for breakfast! - I would just like to know where I went wrong. Thanks!
Kris L. November 8, 2015
I made this last night and had the same issues. Tastes great but wasn't pleased with the watery curdled mess. Ives read all the comments and not one person responded as to what went wrong or maybe it's supposed to look like that?????
Barbara November 17, 2015
Laura 414 wrote she cooks the veggies in the milk mixture until tender but not done then does the layering. She said the milk and cheese doesn't turn into a watery curdled mess. Just so you know you won't always get a response, just sayin
Danielle January 2, 2016
Thanks to all for the responses. I'm going to try this again with your tips!
Anne M. October 31, 2015
Just found this recipe. Looks fabulous. Can it be made ahead and reheated?
Luci Z. October 3, 2015
Oh my, I just made this and it is exquisite! I was determined to make it with what I had on hand, which was a butternut squash, potatoes and two cheeses- Asiago and horseradish-cheddar. So I went with that and threw in a little Parmesan as well. I also used skim milk with a little non-fat half and half rather than whole milk. And it came out perfectly delicious. A real keeper, this one! I can't stop eating it.
Wanderwoman October 2, 2015
Did anyone have any problems slicing the parsnips with the mandolin? They're so pointy I imagine the slices up to the middle part would be so tiny that at 1/8" thickness they'd disintegrate into the dish. Also, was it difficult to form those bitty slices into concentric circles?
Patricia December 28, 2014
Well, the recipe stated 'repeat twice' while adding the cheese, but as I had commented earlier on, I FORGOT the cheese and because it did not NEED to look pretty for that occasion, I threw caution to the wind and tossed all with the cheese ...made NOT a difference to the GREAT taste!!!
Author Comment
Merrill S. December 28, 2014
Love your laissez-faire approach (sounds exactly like something I would do), and glad it all worked out!
rpkc15 December 28, 2014
I am making this now and have a quibble with how the recipe is written. Step 4 says to layer the vegetables, so I did that, but then it says to put the cheese between the layers. So I had to un-layer and add the cheese. It does smell very good. Used the cuisinart to slice as my madeline was not really sharp enough for these roots!
Author Comment
Merrill S. December 28, 2014
As Patricia mentioned, the recipe does say to create one layer of vegetables, sprinkle with cheese and then repeat this process twice more (for a total of three layers of vegetables, with cheese in between each). Apologies if you were confused by the way it was written, and hope it turned out OK!
marynn December 26, 2014
Ok, late to the party, here! I made this for Christmas Dinner to keep company with a Roast Crown Pork Roast with Gorgonzola Sauce (credit: Epicurious and Serious Eats). All I'm saying is, why bother with the roast? Just hand me a spoon for this. Even veg-suspicious husband thought this was outstanding. Merrill, this is outstanding! I made it as directed (was tempted to up the herbs, but respected your expertise and did not) and swapped out the Russet for a white sweet potato. Might offset the cheese? >;) This is a signal dish! Thank you so very much.
Author Comment
Merrill S. December 28, 2014
So glad it was a success!
AK December 23, 2014
Somehow I picked up a container of fresh sage instead of thyme. Any thoughts on how that would work out in this dish?
Author Comment
Merrill S. December 23, 2014
I think it would be nice!
AK December 23, 2014
Thank you! I will give it a try, then.
Trish November 26, 2014
Thank you! Happy Thanksgiving, I appreciate it.
Trish November 26, 2014
Can someone please answer the question if this can be prepped with or without the liquid ahead of time. Say a day before. Pleas. Thank you
Terry A. November 26, 2014
Yes, assemble without the liquid ahead of time - a day ahead. The potatoes tend to discolor a bit when sitting, so toss them in the smallest amt. of olive oil before adding them to the dish to prevent discoloration. Add the liquid just before baking. Let us know how it turned out.
Author Comment
Merrill S. November 26, 2014
The potatoes and parsnips will discolor a little if you assemble it ahead without baking, but that may not matter to you. Don't forget to cover it tightly and refrigerate until you're ready to add the liquid!
robin L. December 17, 2014
any other make-ahead ideas/successful attempts? i'd like to make it a day ahead, either completely or as suggested here just up to the point of assembling then adding the liquid before baking the next day...
Meg I. November 25, 2014
I make this same dish with local turnips (gilfeather turnips) which is totally delicious. Even better with other root vegetables. Thanks for the idea!!
Patricia November 17, 2014
Ooops, I forgot to add that I had bought the baby white potatoes, and just washed and sliced with their skin on ... a plus!
Patricia November 17, 2014
HOO BOY... I am in love with this NEW roots gratin . I am totally unfamiliar with parsnips and hated the THOUGHT of them, but gamely got all the ingredients because your photo looked so scrumptious. I gratefully used my mandolin, and everything looked beautiful in its individual layers ... was about to put in the oven and realised I had forgotten the cheese!! I was making it late in the evening so did NOT have time ... I threw the cheese in and tossed it all together. I can honestly say that I am RAVING about this and parsnips will now be in repertoire. Thanks for an amazing dish which could almost turn me vegetarian!! No liquid as a problem, but the smell must have driven my neighbor mad. BRAVO
robin L. November 11, 2014
...Any suggestions how I can make this up to a point, then finish it when I want to serve it?
Adam D. November 2, 2014
Just made this tonight, but substituted Comté as it's what I had on hand (though I love Gruyère). It was fantastic, and goes straight on to the "Must make this regularly" list. Thanks!
clintonhillbilly October 16, 2014
Made this last night and it was delicious! No problems with extra moisture--I used white potatoes. I didn't know you could infuse milk with garlic---thanks!
Mary A. October 12, 2014
This is AMAZING!!! Made it for a family get-together 2 days ago and everyone (2 year old granddaughter through 90 year old dad) raved about it. Had to leave out the parsinips since local grocery store didn't have them; increased the butternut squash and potatoes to 1.25 lbs of each, milk to 2 cups, cheeses to 1.5 cups each and made in a 9x12 ceramic pan. Only problem... not a crumb leftover to take home. Don't think leaving out the nutmeg would make a lot of difference since nutmeg flavor wasn't apparent.
AntoniaJames October 10, 2014
Merrill, is there any reason not to halve this, for a smaller group? I plan to test this -- serving it as the main with greens for a Sunday supper -- for just the two of us here. Would you adjust the ratios at all? Thank you! ;o). P. S. I cannot help thinking that the leftovers + a few eggs would make a memorable frittata later in the week.
Author Comment
Merrill S. October 10, 2014
I don't see why you wouldn't!
Terry A. October 10, 2014
I made this tonight in a 9x13 glass pan. I made each layer consisting of one root vegee. I put the herbs and S&P on the top of the top layer of veg and then added the cheeses on top of that. I used swiss instead of gruyere. The house smelled amazing, it looked amazing and I just had a taste before bed - TO DIE FOR.
Author Comment
Merrill S. October 10, 2014
Love the idea of using a veg for each layer! Glad you enjoyed this.
A. October 9, 2014
Made this recipe exactly as described for my weekly foodie group dinner. While the diners raved about it, I was disappointed with all the watery liquid the veggies dumped into the dish. Want to know how to avoid this! Parboil the veggies, dehydrate in the oven, on the counter, what? I was not happy with this dish's wateriness even though it tasted OK (not a huge rosemary & thyme fan)
AntoniaJames October 10, 2014
I've seen recipes for vegetable gratins that call for a light dusting of flour on the bottom of the dish and between several of the layers, for this reason. Thanks for the heads up, A. ;o)
Sarah October 10, 2014
I've made a variation of this gratin recipe that called for drying the potatoes on a dish towel or paper towels for awhile before assembling. It worked really well, and I suspect it would help with this dish, too. Making this exact recipe tomorrow, and I can't wait!
AntoniaJames October 10, 2014
I'd worry that by patting them, you'd also be taking the starch off the potatoes, which seems badly needed, especially with the water released from the not-starchy squash and parsnips in this recipe. ;o)
AntoniaJames October 10, 2014
Maybe if you cook the potatoes slightly in the milk that would release more starch . . . you still need to account for the potatoes comprising but only 1/3 of the vegetables, and the liquid thrown off by the parsnips and squash -- especially nice fresh ones. <br /><br />Both of those will continue to release liquid, even after cooking. I make a butternut and parsnip mash on a fairly regular basis, and have found that the next day, the leftovers are sitting in a pool of liquid that wasn't there when I plopped them in the serving dish the day before. Something to keep in mind, especially when making this in advance, as many people might be inclined to do in preparation for a holiday meal. I'd be most interested in anyone's experience with making this ahead of time. ;o)
AntoniaJames October 10, 2014
And, looking at this from another angle . . . could some of the liquid be coming from the milk? I always use a fair bit of cream when making a Dauphinoise . ;o)
Author Comment
Merrill S. October 10, 2014
Hmm, I have never had trouble with excess liquid using this method -- I do always choose a denser potato, which may help.
Mary A. October 12, 2014
I also made this dish in a 9x13 ceramic pan, and I didn't have any issues with liquid. I didn't use parsnips as the local store didn't have any... maybe they are the culprit?
Cecilia F. November 4, 2014
Just took this dish out of the oven and am sad to report I had tons of water sitting at the bottom :( The top looked perfect though! The cheese also was not cheesy at all; it looked...curdled? Like bits of poached egg whites. I followed the recipe quite closely so not sure where I went wrong :(
jenny.g October 8, 2014
very, very delicious! <br />A bit labor intensive (I don't have a mandolin) and I don't have the most precise knife skills, but it turned out perfectly. My new favorite root veggie recipe!
Author Comment
Merrill S. October 10, 2014
Impressive slicing!
Veronica S. October 6, 2014
Definitely going to try this, Merrill -- you make it sound so easy, not to mention yummy!
phyllisc October 6, 2014
Sorry, meanest to type "thoughts" not "toughest"
phyllisc October 6, 2014
Any toughest about making this ahead of time?
Author Comment
Merrill S. October 10, 2014
How far ahead?
Melissa M. October 16, 2014
I'd also love to make ahead - just a day. Thoughts?
canative October 6, 2014
Made this tonight and it was a hit. I used a combo of Yukon gold and sweet potato instead of white. It's great as a main dish with sauteed greens or a salad.
Author Comment
Merrill S. October 10, 2014
Glad you liked it!
AntoniaJames October 5, 2014
Oh, we will! I usually combine mashed parsnips and mashed butternut squash for one side dish, and make scalloped potatoes as a second; looking forward to this combination. ;o)<br />
Hina October 5, 2014
Looks amazing! Do you think you could eliminate white potatoes altogether and add another squash?
Author Comment
Merrill S. October 5, 2014
Yes, sure - or you could use sweet potato.
PamCap 2. October 5, 2014
I o not like nutmeg - thoughts on making without nutmeg??
Author Comment
Merrill S. October 5, 2014
You can leave out the nutmeg, and it will be just fine!
kissy28c October 6, 2014
Glad to hear it. Will try it this way too!
Laura R. October 4, 2014
Will need to test this out on the family a few times before Thanksgiving!
AntoniaJames October 4, 2014
Ditto!! ;o)
AntoniaJames September 30, 2014
Whoa. This looks utterly amazing. Definitely on the must-try list; I fully expect it to find a place in my most important special-occasion collection (recipes for when the boys are home!) ;o)
Author Comment
Merrill S. October 5, 2014
Hope you like it!