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French Onion Tart - Panning The Globe

French Onion Tart Recipe

  • Author: Lisa
  • Total Time: 3 hours
  • Yield: 8 1x


A savory vegetarian tart of braised onions and eggs baked in a mustard-coated tart shell, topped with thyme and olives. Perfect for brunch or dinner.


Units Scale

For The Tart Shell 

  • 1 stick cold unsalted butter
  • 1 cup unbleached all-purpose flour
  • 1/4 teaspoon salt
  • 3 tablespoons cold water

For The Filling

  • 3 tablespoons olive oil
  • 4 large onions, thinly sliced (about 6 cups)
  • 1 teaspoon salt
  • 2 eggs, whisked
  • 1 tablespoon dijon mustard

To Garnish

  • 5-6 thyme sprigs
  • 6-8 Niçoise olives


  1. To make the tart shell, cut butter into small chunks and transfer to the bowl of a food processor fitted with the s-shaped chopping blade. Add flour, and salt. Pulse about 10 times. Then add the water and pulse about 10 more times or until the texture resembles cornmeal. Pour the mixture onto a clean surface and, using the heal of your hand, press it little by little, until the butter and flour are incorporated. Gather it into a ball. Flatten the ball into a disc. Cover with wax paper and refrigerate for 15 minutes, to firm it up a bit. Generously dust your work surface and rolling pin with flour to prevent sticking. Remove the dough from the fridge and roll it into a 13-inch circle. Line a 9 or 10-inch tart pan with the dough, trimming off the excess. Make several pricks in the bottom with a fork and refrigerate for 2 hours. (It can also be frozen until you're ready to use it)
  2. Preheat oven to 400ºF. Cover the tart shell with foil and fill the bottom with dried beans. Bake it in the middle of your oven for 10 minutes. Remove the beans and foil and bake for another 5-10 minutes. You want the bottom to dry without coloring.
  3. Preheat the oven to 425ºF. In a large dutch oven or heavy pot combine olive oil, sliced onions, salt and 1/4 cup of water. Heat the mixture until it starts to sizzle, then turn the heat down to a simmer, cover, and cook for 30 minutes, stirring occasionally. Spoon onions into a mixing bowl and set aside until cool. Pour off liquid that has accumulated around the onions and combine eggs with onions.
  4. Spread mustard over the bottom of the pre-baked tart shell, using a pastry brush. Spread the onion mixture evenly on top. Make a pretty pattern on top with the thyme sprigs and olives. Bake in the middle shelf of the oven for 30-40 minutes, until the top is golden brown. Serve at room temperature, cut into wedges.


TIME SAVING TIP: To make this recipe quick and easy, use a store-bought pie crust.

  • Prep Time: 2 hours
  • Cook Time: 1 hour
  • Category: Side dish
  • Method: Bake
  • Cuisine: French

Keywords: Onion tart, savory vegetarian tart