Gruyere and Caramelized Onion Tart Recipe

Serving: 6 portions

Equipment

Mixing bowl
Food processor
Plastic film
Sartén grande
10-inch tart pan [20 centimeters]
Parchment paper
Pie weights (or dry beans, or any dry pulses)

Ingredients

FOR THE CRUST

1¾ cup whole-wheat flour
¾ teaspoon salt
1 teaspoon baking soda
⅓ cup unsalted butter melted
1 egg
½ cup cold water may not need all

FOR THE FILLING

¼ cup olive oil
3 pounds white onion [1.4 kilogram], halved and sliced thinly
½ teaspoon fresh thyme leaves or dry if you don't have fresh
½ cup cooking sherry
1 tablespoon garlic salt (see notes)
1 teaspoon black pepper freshly-cracked, or ground
½ teaspoon nutmeg freshly grated
2 tablespoons all-purpose flour
1 cup grated Gruyère cheese
½ cup shredded sharp cheddar

Instructions

1. Mixing ingredients for the crust

In a mixing bowl, mix flour, salt, and baking soda. Pour the mix into the food processor.
Pour in melted butter and egg, and pulse to incorporate. Midway stop and scrape the sides with a spatula moving the flour from the sides to the middle. If the dough is too dry, add cold water by the tablespoon until the dough just forms a ball but is not soggy or sticky.

2. Making the dough

Pour onto the counter and knead the dough lightly until it is smooth (about 1 minute).
Wrap in plastic film and let it rest at room temperature for at least 10 minutes.

3. Caramelizing the onions

Heat the oil over medium-low heat in the skillet. Add the onions and thyme and stir until the onions are coated with oil. Cover and simmer over for 5 minutes, stirring often.
Add the sherry, and simmer until the sherry has mostly evaporated. Cover and simmer over low heat for another 25-30 minutes, or until the onions have turned caramel brown and are very tender.
Season with garlic salt, pepper, and nutmeg.

4. Add the flour

Increase heat to medium-high heat and add flour, sprinkling, and mixing until all the onions are lightly coated with flour. Remove from the heat.
Let it rest until the onion mixture has cooled to room temperature.

5. Preheating the oven

Heat oven to 350 ºF [175 ºC].

6. Forming the crust

Roll out the dough with a rolling pin until you have a circle big enough to cover the bottom and sides of the tart pan.
Cover the tart pan with the dough and tidy up the sides using any excess dough. Poke a few holes in the bottom with a fork. Line the bottom with a circle of parchment paper, and place the pie weights or dry beans on the parchment paper.

7. Baking the pie

Bake the pie crust in the preheated oven for 15 minutes. Remove from the oven.
Fill the pie crust with the onion mixture, and top with the cheeses.

8. Melting the cheese

Return to the oven and bake until the cheese is bubbly and golden brown.
Remove from the oven and serve hot.

Cook's notes

If you don't have garlic salt mix ½ tablespoon of regular with ½ tablespoon of garlic powder.

You can make this French onion tart with puff pastry for a different and entirely marvelous variation. Instead of making the crust as directed, just bake a circle of puff pastry (unweighed) on the bottom of the tart pan.

Whole wheat dough is very fragile, and not at all elastic like regular dough, I've found that the best way to spread it is doing it between two plastic film pieces. There's going to be some patching too. Don't worry too much, that's why I called it "rustic".

Nutrition

5 from 1 vote