French Onion Tart



Author Notes: The seedling of an idea for this recipe started while I was making cheddar cheese crackers for the kids. The thought occurred that it might be an interesting base for a tart crust.

As I wandered through the farmers' market later that day, in search of some "late winter" inspiration, a bunch of humble onions set the ball rolling. It was at the moment I knew I wanted to recreate the flavors of a French onion soup into my tart. While the directions seem long, it really does come together effortlessly, and well worth the time it takes to caramelize the onions.
Jennifer Perillo

Food52 Review: WHO: Jennifer Perillo is a mother, a food editor, and a blogger at In Jennie's Kitchen.
WHAT: French onion soup, re-imagined and re-packaged in tart form.
HOW: A filling of caramelized onions, thyme, Swiss cheese, sherry vinegar, and egg is poured into a whole wheat crust and baked.
WHY WE LOVE IT: The cheesey, whole wheat crust is tender and lovely, a perfect foil for the sweet, onion-loaded filling. The sherry vinegar keeps the whole tart balanced. And just like the soup, this tart is deeply satisfying...but not so rich that you can't eat two slices.
The Editors

Serves: 6 to 8

Ingredients

For the filling

  • 1 tablespoon extra virgin olive oil
  • 2 pounds yellow onions, peeled & sliced thin
  • 2 sprigs fresh thyme, leaves removed & stems discarded
  • Sea salt and freshly ground pepper, to taste
  • 1 large egg, lightly beaten
  • 1 teaspoon sherry vinegar
  • 2/3 cup (2 ounces) Swiss cheese, shredded

For the Swiss cheese pastry crust

  • 3/4 cup (110 grams) whole wheat pastry flour
  • 1/4 teaspoon (2 grams) fine sea salt
  • 1/4 teaspoon paprika
  • 1 cup (3 ounces) Swiss cheese, shredded
  • 4 tablespoons (2 ounces) very cold butter, shredded using a box grater
  • 1 to 2 tablespoons cold seltzer

Directions

  1. To make the filling, heat the olive oil in a heavy-bottomed pot over medium-high heat. Add the onions and saute for 2 minutes. Cover pot, reduce heat as low as it can go without shutting off, and let cook until onions have cooked down and released a lot of their liquid, about 20 minutes.
  2. Meanwhile, prepare the crust. Add the flour, salt, and paprika to the bowl of a food processor. Pulse once or twice to mix the dry ingredients. Add the cheese and butter, then pulse a few times until it forms a sandy-looking mixture. Add 1 tablespoon of seltzer, pulse again until a rough ball of dough comes together. If the mixture is too dry and crumbly, add more seltzer 1 teaspoon at a time (you may not need the entire 2 tablespoons), and continue to pulse until you have a ball of dough. Turn the dough out onto an unfloured counter, flatten and shape into a disk. Wrap in plastic wrap and chill for 30 minutes.
  3. Preheat the oven to 400ºF.
  4. Remove cover from the pot of onions, raise heat to medium, add the thyme and season with salt and pepper. Let the onions cook, stirring occasionally to scrape the browned bits from the bottom of the pot, until onions turn golden brown, about 30 to 35 minutes. When onions are golden and very tender, stir in the sherry vinegar. Remove from heat and, using a slotted spoon, transfer onions to a medium bowl.
  5. Place the chilled dough between two sheets of parchment paper, and roll it into a 13-inch circle. Fit dough into a 9-inch ungreased springform pan. Fold down sides of dough, leaving a 1-inch high crust.
  6. To finish the filling, add the egg and cheese to the bowl with the onions. Stir to mix well. Pour mixture over the tart crust and spread to the edges using a rubber spatula. Bake for 25 minutes, until slightly puffed and golden. Remove from oven and let cool for 5 to 10 minutes before slicing.

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Reviews (73) Questions (7)

73 Comments

erin March 21, 2018
I made this last night and we loved it - it's rich and comforting without being overwhelming. A few comments/ideas: 1. I used gruyere because I always use that for onion soup, and I think the nutty flavour was helpful here; 2. The crust is a little fragile but I just patched and squished where necessary; 3. I prebaked the crust for 20 minutes but should have stopped at 15 because it went a smidge over in the end, but because it's such a cheesy crust that's less disastrous than it might otherwise have been; 4. I added an extra egg because the filling would have been sparse otherwise; 5. I crisscrossed the top with anchovies and black olives, pissaladiere style, and loved that salty sharpness against the onions. As dinner in its entirety (just some arugula on the side) this is really four portions in my house and I don't think we're especially gluttonous...
 
Miss K. December 16, 2017
Snarf! Next time I am going to use smoked Gruyere cheese....
 
Sara P. November 15, 2017
Does anyone have experience adding additional ingredients to pre-made refrigerator dough
 
Sarah March 16, 2015
I was not 100% successful with this (was in bit of a rush and didn't let the onions brown enough, methinks), but I just wanted to say that the crust was EXACTLY like a Ritz cracker (but more delicious) and I found this pretty amazing.
 
caroline January 4, 2014
What can I substitute Sherry Vinegar with? I just don't want to buy one whole bottle and rarely use it. Thanks. <br /><br />
 
cratecooking February 5, 2013
This tart is FABULOUS!!!!
 
LoisG February 2, 2013
can you make this ahead of time? like the day before?
 
Bozemanchef December 3, 2012
I have made this (very similar tart) using a cornmeal crust. Also very delicious and adds an interesting texture. One of my favorite savory tarts!...
 
InjunTrouble November 15, 2012
This looks absolutely divine. Making this very soon. YUM
 
Patricia M. November 1, 2012
I get Amanda's email every week, with great recipes, but i noticed just on this last <br />email that the right margin is cut off and sometimes you can make up the cut off words but sometimes i can't. Can you please see to it so that my recipes come in intact.? <br />Thank you very much, Tricia
 
Karenmwaters October 27, 2012
In making the crust in the food processor, can I just use the regular metal blade? I have an old one and can't find the bread blade.
 
Kristen M. October 27, 2012
Yes, I think the regular blade is perfect here (or at least that's what I always use to cut fats into flours for doughs like this).
 
Manhattan T. October 24, 2012
Is there ANY way to delete the numerous, repetitive comments here? I made the tart tonight and was annoyed, every time I consulted the comments section, by having to troll through them... I used about 2 1/3# of onions and cooked them, lid on then lid "cracked," for about 75 minutes (they never browned per se but developed that lovely texture of caramelized goodies). I used fontina (what I had on hand) and 2 eggs for a slightly more custard-y texture (which didn't work, but that was soooo okay) and a 10", removable-bottom tart pan. The crust was a bit fussy (using 3/4 c. WW flour, 1/4 AP) but totally delicious, as was this tart. Serve this baby with simple greens and you are DONE, my friend. It's fabulous.
 
geneenb October 10, 2012
This was delicious! I didn't have wheat pastry flour but I had regular wheat. I used 1/2 cup of that and 1/4 cup AP flour. Also I used red wine vinegar instead of sherry. Turned out great! Crust was easy to roll out without parchment.
 
Sauertea October 8, 2012
So I added garlic and some nutmeg. Thinking of trying a cornmeal crust. Very good but found the pastry hard to roll out.
 
Sauertea October 8, 2012
So I added garlic and some nutmeg. Thinking of trying a cornmeal crust. Very good but found the pastry hard to roll out.
 
Sauertea October 8, 2012
So I added garlic and some nutmeg. Thinking of trying a cornmeal crust. Very good but found the pastry hard to roll out.
 
Sauertea October 8, 2012
So I added garlic and some nutmeg. Thinking of trying a cornmeal crust. Very good but found the pastry hard to roll out.
 
Sauertea October 8, 2012
So I added garlic and some nutmeg. Thinking of trying a cornmeal crust. Very good but found the pastry hard to roll out.
 
tastysweet October 8, 2012
Is there a temperature to check in case we use a different type of pan?
 
putaneggonit October 7, 2012
Amazing! The filling was delicious, with excellent texture, and the crust - oh my goodness, the crust! You're right, it is surprisingly delicate. Thanks so much, wonderful recipe.