Prep time: 30–40 min
Bake time: 40 min
1 store-bought puff pastry
All-purpose flour for dusting
3–4 medium-sized vine-ripened tomatoes
1 tsp granulated sugar (optional)
Salt, preferably a finishing sea salt such as Maldon
4 oz fontina cheese
Fresh thyme leaves
Extra-virgin olive oil
Freshly ground black pepper
Finishing olive oil
Preheat oven to 375°F. Line a shallow rimmed baking sheet with parchment paper. Unfold the puff pastry onto a lightly floured surface. Use a rolling pin to roll the pastry into a ¼-inch thick rectangle (about the shape of the baking sheet). Slice tomatoes and sprinkle them with the optional sugar and a pinch of salt.
Gently roll the pastry over a rolling pin and unfold onto the lined baking sheet. Using the tip of the knife, lightly score a border about ½-inch from the edge of the pastry (do not slice all the way through). Prick the dough inside the border all over with a fork to prevent puffing during baking.
Grate cheese and sprinkle inside the pastry border, and then arrange tomatoes in a single layer in this same area. Scatter thyme leaves over the tomatoes. Drizzle with olive oil and season with black pepper.
Bake the tart until the pastry is crisp and deeply browned on the bottom and edges, about 40 minutes. Remove from the oven. Drizzle with additional olive oil and sprinkle liberally with sea salt. Cut into portions and serve.