Celebrate the end of summer with this beautiful vegetable tart! It’s filled with sweet caramelized onions and tomatoes, then topped with seasonal squash. Keep this recipe in mind as you visit your local farmers’ market.
Summer Squash and Tomato Tart with Caramelized Onions and Gruyere Cheese
Makes one 9-inch tart
Crust Ingredients:
2-1/2 cups all-purpose flour
1 teaspoon Kosher salt
1 cup (2 sticks) unsalted butter, cold and grated
2 egg yolks
1/4 cup ice cold water
Filling Ingredients:
1 large yellow onion, chopped
2 cloves garlic, sliced
3 Campari tomatoes, diced
1 small zucchini
1 small yellow squash
1/2 teaspoon Kosher salt, divided
1 cup Gruyère cheese, grated and divided
2 tablespoons unsalted butter
Drizzle of extra virgin olive oil
Salt and pepper
Directions:
1. In a large bowl, whisk together the flour and salt.
2. In a food processor, pulse the flour, salt, and butter together. The texture should be coarse with some pea-sized pieces of butter remaining.
3. Add the egg yolks and 1 tablespoon of ice water. Continue to pulse until just combined. Add additional ice water 1 tablespoon at a time until fully incorporated. The dough will still be a loose, crumbly mixture in the food processor -- this is correct. Avoid adding too much water or pulsing too much.
4. Empty the dough onto a work surface and gather the dough into a ball, then flatten it into a 1/2-inch thick disk. Wrap the disk in plastic wrap and chill in the refrigerator for an hour, or overnight.
5. Once chilled, roll the dough out into a round shape roughly 1/8-inch in thickness, and place in a tart pan with a removable bottom. Use a sharp knife to trim the edges at the top of the tart pan and chill the dough again in the pan for one hour.
6. Preheat the oven to 375 F. Dock or prick the crust with the tines of a fork to vent the crust as it bakes. Place pie weights or use dried beans on parchment inside the tart crust. Bake for 20-25 minutes or until the edges are beginning to turn golden brown. (Baking times will vary based on the pan and crust thickness.) Allow the tart crust to cool in the pan on a cooling rack while preparing the filling.
7. While the tart crust bakes, prep the vegetables. Thinly slice the onions and the garlic. Slice the zucchini and yellow squash with a mandoline. Place the squash in a bowl and sprinkle with salt; toss to coat. Set aside. Grate the cheese.
8. In a large sauté pan over medium heat, melt the butter and cook the onions until they start to soften. Sprinkle with the salt and reduce the heat to medium-low. Continue to cook until the onions are deeply brown and caramelized, roughly 20-30 minutes.
9. Add the sliced garlic and cook for 2-4 minutes until softened. Then add the tomatoes. Cook until the tomato juices have evaporated, about 5-8 minutes.
10. Spoon the onion and tomato base onto the baked crust. Sprinkle with half of the Gruyère cheese, then top with the zucchini and squash slices. Make a pretty pattern if you'd like! Drizzle with olive oil, a sprinkling of salt and pepper, and the remaining cheese. Bake for 20 minutes until the cheese is nicely melted. Cool slightly on a cooling rack. Serve warm.