Preheat the oven to 400°. On a lightly floured work surface, using a lightly floured rolling pin, roll out each sheet of puff pastry to a 13-by-9-inch rectangle. Stamp out six 4-inch rounds from each sheet. Transfer 6 rounds to a parchment paper–lined baking sheet. Roll out the remaining 6 rounds so they are slightly larger, about 4 1/2 inches in diameter.