French Onion Galette

If you love French Onion Soup, then this rustic French Onion Galette
is for you; caramelized onions with Gruyere cheese and thyme on a flaky crust.

Course Appetizer, Pastry and Pie

Cuisine French

Keyword french onion, gallette, pie

Prep Time 30

Cook Time 1 30

Total Time 2

Servings Servings

Calories 519kcal

Author Barb

Ingredients

For the crust

8 tablespoons butter 1 stick, cold
1 ½ cups all-purpose flour plus more for dusting
1 teaspoon freshly ground black pepper
½ teaspoon kosher salt
¼ cup plus 3 tablespoons ice water

For the Filling and Assembly

3 pounds yellow onions about 3 large or 6 medium
10 sprigs fresh thyme
3 tablespoons unsalted butter
1 teaspoon kosher salt
½ teaspoon black pepper freshly ground
6 ounces Gruyère cheese
¼ cup dry white wine
2 teaspoons balsamic or sherry vinegar
2 teaspoons Dijon mustard

Instructions

Make the Crust

Freeze 1 stick cold unsalted butter until firm, about 15 minutes. Meanwhile, whisk 1 1/2 cups all-purpose flour, 1 teaspoon black pepper, and 1/2 teaspoon kosher salt together in a large bowl.
Place a box grater over a small piece of parchment paper, cutting board, or large plate. Grate the butter on the large holes of a box grater. When you get down to a small nub of butter, chop that nub into 5 to 6 small pieces. Reserve the grater (no need to clean).
Transfer the butter to the dry ingredients and reserve the parchment paper. Use your fingers to toss the butter in the flour, breaking up any clumps, until evenly coated.
Drizzle 1/4 cup plus 3 tablespoon ice water over the butter-flour mixture. Use a fork or your hands to combine and lightly mix until a rough dough ball forms; do not overwork the dough.
Turn the dough out onto a large piece of plastic wrap. Use the palm of your hand to quickly gather and press the mound into a thick disk. Wrap in the plastic wrap and refrigerate while you prepare the filling, at least 1 hour.

Make the Filling

Halve and thinly slice 3 pounds yellow onions (about 11 cups). Strip the leaves from 10 fresh thyme sprigs.
Melt 3 tablespoons unsalted butter in a 12-inch or larger, preferably high-sided, skillet over medium heat. Add the onions, half of the thyme leaves, 1 teaspoon kosher salt, and 1/2 teaspoon black pepper. Cook, stirring frequently with a wooden spoon and reducing the heat if the onions start to burn, until the onions have reduced by over half, are very soft, and deep golden brown, 45 to 60 minutes.
Meanwhile, grate 6 ounces Gruyère cheese on the large holes of the box grater onto the reserved parchment paper (about 1 1/2 cups).
Pour 1/4 cup dry white wine over the caramelized onions. Scrape up any browned bits on the bottom of the pan and continue to stir until the wine has evaporated, about 1 minute. Remove from the heat and stir in 2 teaspoons balsamic or sherry vinegar.

Assemble and Bake the Galette

Arrange a rack in the middle of the oven and heat the oven to 400°F. Prepare a sheet of parchment paper about the size of a baking sheet. Lightly dust the parchment with all-purpose flour.
Unwrap the dough and place it on the prepared parchment paper. Sprinkle the dough with more flour and, using a rolling pin, roll it out into a round about 12 inches wide. Carefully transfer the parchment paper, with the rolled-out dough on it, onto a baking sheet.
Spread 2 teaspoons Dijon mustard evenly onto the dough with the back of a spoon or a butter knife, leaving a 1 1/2- to 2-inch border. Sprinkle half of the cheese onto the mustard. Spoon the caramelized onions onto the cheese.
Gently fold the edges of the dough over the filling, pleating it about every 2 inches. Sprinkle the remaining cheese on top. (Don’t worry if some of the cheese gets on the crust — it will just result in some nice, golden-brown crispy bits like French onion soup!)
Bake until the crust is firm and golden-brown, and the cheese is melted and browned in spots, about 35 minutes.
Let the galette cool for at least 5 to 10 minutes before serving. Garnish with the remaining thyme leaves and serve warm or at room temperature, cut into wedges.

Notes

Storage: Wrap leftovers tightly in plastic wrap and refrigerate for up to 4 days. Re-warm in a 300°F oven.

Make ahead: The dough and caramelized onions can be made a day ahead of time. Store both in the refrigerator and let the onions sit at room temperature while the oven preheats before rolling out the dough and assembling.

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