Potato Leek Au Gratin

September 21, 2009
7 Ratings
  • Serves 4 to 6
Author Notes

This is one of my favorite fall recipes because it is just perfect with a roast or paired with lamb chops. For a more robust dish, use the maximum amount of gruyere. Butter is optional but not the the vermouth which adds nice depth of flavor. It is important that the potatoes be close to uniform in size so that they all cook evenly (and most importantly, don't get too soft). The end result should be tender potatoes steeped in a rich flavorful cream sauce. Finally, ENJOY! —AlexisC

Test Kitchen Notes

The secret to a great gratin is not trying too hard. Potatoes are delicious; there’s no need to smother them. And this is a point that AlexisC clearly gets. Her potatoes are gently scented with leek and garlic and enriched with cream and Gruyere. AlexisC has you bake the gratin at a fairly low temp – 300 degrees – so by the time the gratin emerges from the oven, the layers of potato are buttery in texture and topped with a crisp, caramelized crust. As for all gratins, buy yourself a mandoline (the best are the inexpensive Japanese-style ones) – it will preserve your sanity and make for uniform slices. - A&M —The Editors

What You'll Need
  • 2 Leeks (medium size)
  • 1 Garlic Clove
  • 1 splash Vermouth (or dry white wine)
  • 2 to 2 1/2 pounds Boiling Potatoes (approx 6-7medium size potatoes such as Yukon Gold)
  • 1 to 1 1/4 cups Grated Gruyere
  • 1 1/4 cups Heavy Cream
  • 2-3 tablespoons Unsalted Butter
  • Kosher or Sea Salt (to taste)
  • Pepper (to taste)
  • 1 small saute pan
  • 1 10 inch long / 2 inch deep baking dish.
  • 4-5 Shavings of Gruyere
  1. Preheat oven to 300 degrees.
  2. Remove roots and green leaves from leeks. Wash and dry the white part of the leek.
  3. Split leeks in half lengthwise. Then chop crosswise into thin to medium size half moon crescents. Dice garlic
  4. Sauté leeks slowly in approximately one tablespoon of the butter on medium low heat in a nonstick pan until soft but not brown (about 6-8 minutes). Add garlic and sauté for a minute more. Add a dash of vermouth (or white wine) and sauté a minute more until most of the vermouth (white wine) has evaporated. The leeks should be damp, but not swimming in vermouth (white wine). Remove leeks from heat, cover and let sit.
  5. Peel and slice potatoes evenly into approximatly 1/8 inch slices. Dump slices in cold water as you slice so that the potatoes don’t turn brown. (note: I peel and slice each potato individually rather than peeling them all first so that the peeled potatoes spend less time sitting around possibly turning brown.)
  6. Grate a block of gruyere so that you have 1 cup of grated gruyere.
  7. Lightly butter the baking dish. Drain potatoes taking care not to break them.
  8. Lay down one layer of potato in the dish. Sprinkle generously with salt and pepper. Then sprinkle with sautéed leek mixture. Then sprinkle with some of the gruyere. Finally dot with one or two bits of butter (optional). Repeat sequence until all potatoes are used. The last layer should be just a layer of potatoes.
  9. Slowly pour cream all over potatoes in dish. Finish with a few shavings of gruyere which will give a nice color and a little bit of crust. Bake for approximately 1 ¼ to 1 1/2 hours. Cream should simmer and may even gently bubble, but it should never boil (boiling will cause the cream to separate and curdle). It’s done when it has a nice golden brown / orange color; the potatoes are tender but still hold their shape; and the cream has thickened and reduced slightly. Let cool for 15-20 min before serving.
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14 Reviews

Teton M. December 25, 2023
Lovisa W. December 27, 2022
This was a great recipe. I have tried a number of different leek and potato au gratin and this is by far the best version! I think the vermouth makes all the difference. The only modification I made was to increase the amount of gruyere and top with a mix of gruyere and parmesan. I forgot to read the reviews in advance and didn't blot the potatoes. I had no issues with a watery sauce. It was absolutely perfect with my roast rack of lamb and sauteed brocolini. I'm serving leftovers tonight with a sauteed pork. I'm sure it will be even better tonight!
Sabine G. December 21, 2019
I made this exactly as laid out and it was phenomenal. The only difference is mine took a bit longer to cook. My potatoes were thin so I don't know why. Regardless, this is a MUST. It's excellent. Flavors are incredible. Everyone loved this dish! Making again for Christmas dinner alongside our prime rib. Boring baked potatoes are a thing of the past at our holiday dinner! I also dried off each potato so I wouldn't have anything watered down!
judytnelson December 10, 2019
I made this with no substitutions and it was beautiful and delicious. The reviewer's tip to dry the potato slices on a clean dish towel was very helpful.
Ceege March 26, 2013
I made this for a dinner party. So good! It went over well with my guests. A little hint: After I drained the potatoes, I placed them on a clean dish cloth, then put another cloth on top and gently blotted the potatoes. This will get just about all the water off the potatoes and will lessen the chance of a watery finished product.
sunnyside April 9, 2012
I made this for Easter dinner potluck yesterday. It was worth every calorie (and I'm on WW)! I kept revisiting the recipe... should I, or shouldn't I? Gave in. Boy, I'm glad I did! It was a hit with everyone. SUCH a treat and not that difficult. I prepped the cutting and chopping the day before (keeping the potatoes in a large dish of cold water, and put it all together the morning of. Wonderful.
Irina August 25, 2015
Were potatoes okay being kept in the water overnight? Didn't the dish become waterish? I want to do the preparation beforehand as well, but a bit worried about the quality of the result.
GipsyChef March 27, 2012
Here is a Video version of this recipe: http://gipsychef.com/2012/03/26/au-gratin/
creamtea December 22, 2011
This looks delicious. I'm going to try it (probably with lower fat-content half & half). Love leeks with potatoes. It was so nice to meet you at the book signing!
elcue January 31, 2011
Oh, yum! It's on the list. Thanks for sharing.
yquinonez November 7, 2010
I made your gratin yesterday for a dinner party to go along with deer medallions. It was wonderful. Your steps were precise, the amounts exact and the taste delicious, just the exact creamy texture. Thank you.
KitchenKim October 1, 2009
I have potatoes and leeks at home...tomorrow I will buy the rest of the ingredients for this recipe - it looks wonderful...
freedfeld September 28, 2009
Sounds wonderful ,will try this in a few days.

from freedfeld
Kristin September 22, 2009
This sounds delicious, I can't wait to try it!