Caramelized Onion Tart
Flaky pastry, sweet caramelized onions and a creamy egg and Gruyere cheese filling make this onion tart both flavorful and irresistible to serve as an appetizer, dinner or even brunch.
Servings: 6
Ingredients
For the crust (shortcut pastry)
- 1 2/3 cups all-purpose flour
- 7 Tablespoons cold unsalted butter , cut into cubes
- 1 large egg
- pinch of salt
- 1-2 Tablespoons cold water
Caramelized onions
- 3-4 large onions (about 1 pound)
- 2 Tablespoons unsalted butter
For the filling
- 1/2 cup heavy cream , preferably 20–30% fat
- 2 large eggs
- 1 cup grated hard cheese , I used Gruyere
- salt and pepper , to taste
- pinch nutmeg , optional
Instructions
Make the crust
- In a large bowl, combine the flour, salt, and butter. Use your fingertips to rub the butter into the flour until the mixture looks like fine breadcrumbs.
- Add the egg and 1 tablespoon of cold water. Mix and knead gently just until the dough comes together, adding an extra splash of water if needed.
- Shape the dough into a ball, wrap it in plastic wrap, and refrigerate for about 30 minutes to rest.
Caramelize the onions
- While the dough chills, peel and thinly slice the onions into half-rings.
- Melt the butter in a large skillet over medium heat. Add the onions and cook, stirring often, until soft and golden brown, about 20 minutes. Keep the heat moderate so they caramelize slowly without burning.
Prepare the Filling
- In a medium bowl, whisk together the eggs and cream until smooth.
- Stir in the grated cheese, a pinch of nutmeg (if using), and season with salt and pepper.
Assemble and bake
- Preheat the oven to 350°F.
- Roll out the chilled dough on a lightly floured surface and fit it into a 9-inch (23 cm) tart pan. Press gently into the edges and trim off any excess. Prick the bottom with a fork.
- Line the crust with parchment paper and fill with pie weights or dried beans. Blind bake for 10 minutes, then carefully remove the parchment and weights.
- Spread the caramelized onions evenly over the crust. Pour the cream and cheese mixture on top.
- Return the tart to the oven and bake for 25–30 minutes, or until the filling is golden and set.
To serve
- Let the tart cool slightly before slicing. It’s delicious served warm, but also just as good at room temperature.
Notes
- Cheese: Parmesan or Cheddar could also be used.
- Onion: I used red onions, but sweet onions or yellow onions can be used as well.
- Store leftovers in an airtight container in the refrigerator for 3-4 days.