1. Heat oven to 400 degrees F. Line a baking sheet with parchment paper; set aside.
2. On a lightly floured surface, unfold pastry. Using a 3-inch biscuit cutter, cut out 8 to 9 rounds and transfer to prepared baking sheet, placing 1 inch apart.
3. Using a fork, prick each round in several places. Bake 5 min.
4. Sprinkle each round with about 1/2 tsp. Parmigiano-Reggiano, then cover with 1 tomato slice; season with salt and pepper. Top each with 1 mozzarella slice.
5. Bake until pastry is puffed and golden, 12 to 14 min. Sprinkle each tart with basil and serve warm. Makes 8 to 9 tarts.