How to Make It
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.
Mound 1/4 cup of the filling in the center of each smaller pastry round. Brush the edges with some of the beaten egg and top with the larger pastry rounds; press to seal. Crimp the edges with the tines of a fork (recut with a ring cutter if a clean edge is desired). Brush with the remaining beaten egg and cut a small steam vent in the top of each pie. Bake for 25 to 30 minutes, until the pies are golden and puffed. Serve warm.