Summer Squash and Tomato Tart with Caramelized Onions and Gruyere Cheese

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 it into a ball, then flatten into a 1/2-inch-thick disk. Wrap 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 thick, and place in a tart pan with a removable bottom. Trim the edges and chill again in the pan for one hour.
6. Preheat oven to 375°F. Prick the crust with a fork to vent. Place pie weights or dried beans on parchment inside the crust. Bake for 20–25 minutes or until edges begin to turn golden brown. Let the crust cool in the pan on a rack.
7. While the crust bakes, prep the vegetables: slice onions and garlic, and slice zucchini and squash with a mandoline. Place squash in a bowl, sprinkle with salt, and toss. 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 salt and reduce heat to medium-low. Continue cooking until deeply brown and caramelized, 20–30 minutes.
9. Add sliced garlic and cook for 2–4 minutes until softened. Then add tomatoes and cook until juices have evaporated, about 5–8 minutes.
10. Spoon onion and tomato mixture onto the baked crust. Sprinkle with half the cheese, then layer the zucchini and squash slices. Drizzle with olive oil, season with salt and pepper, and top with remaining cheese. Bake for 20 minutes until the cheese is melted. Cool slightly and serve warm.