Red Pepper and Boursin Tarts

Preheat oven to 450 °F. Cook bell peppers in oil in a large nonstick skillet over moderate heat, stirring, until softened, about 8 minutes, then cool. Unfold pastry sheets on a lightly floured surface and cut out an 8-inch round from each. Transfer rounds to a buttered large baking sheet and prick all over with a fork, leaving a 1/2-inch border around edges. Spread 2 tablespoons cheese evenly over each round, then scatter with peppers and sprinkle with thyme, kosher salt, and pepper to taste. Bake tarts in middle of oven until puffed and golden brown, about 15 minutes, then transfer to a rack to cool slightly. Cut each tart into 8 wedges and serve warm.