We ate this as a main dish, but it would make a wonderful appetizer or side dish. It's good warm and at room temperature. If you're serving it to guests, you can make this a few hours ahead--after the tart has cooled, store it, covered, at room temperature until you're ready to serve or reheat it in the oven. Once you refrigerate it, the crust will begin to get a little soggy.
Makes one 9-inch tart
Total Time: about an hour and a half
1 recipe pâte brisée, or your favorite pie/tart dough recipe (you can see mine here), chilled
9-10 oz zucchini, ends trimmed, sliced into 1/8-inch slices
9-10 oz yellow squash, ends trimmed, sliced into 1/8-inch slices
1/2 C thinly sliced onion
1/4 C tomato sauce (try this one!)
1 clove garlic, minced
4 Tbsps extra virgin olive oil, divided
2 tsp kosher salt
freshly ground black pepper
1/2 tsp dried oregano
1/2 tsp dried thyme
1/2 tsp dried basil
2-3 oz feta, crumbled
Place a rack in the middle of the oven and place a baking stone on it. Preheat the over to 400F.
In a medium skillet, heat the remaining 2 tablespoons of olive oil over medium heat and caramelize the onions, stirring often, about 30 minutes. Remove pan from the heat and set aside.
Grease a 9-inch tart pan with a removable bottom and place it over a sheet of parchment paper on a rimless baking sheet.
Once the dough is just warm enough to be rolled out, roll the dough into a 12- to 13-inch circle (about 1/8-inch thick) over a lightly floured surface. Gently roll the dough around your rolling pin and unroll over your prepared tart pan. Press the dough into the sides and bottom of the pan. Roll your rolling pin over the top of the pan to cut off the excess dough. Prick the bottom of the dough with a fork about 10 times.
Spoon the tomato sauce around the bottom of the tart and smooth out with the back of a spoon. Scatter the caramelized onions over the sauce. Alternating zucchini and yellow squash, layer overlapping slices in concentric circles until the tart is filled. Place the pan in the oven on the baking stone and cook for 40-45 minutes, rotating the pan halfway through cooking time. The vegetables should be tender and starting to brown in spots. Remove from the oven and cook on a cooling rack for 5 minutes. Sprinkle on the feta crumbles, slide the tart with the parchment off of the pan and let the tart cool a bit more until you can remove it from the pan and enjoy!