Heat oven to 400 degrees. Defrost pastry dough, following label directions. In a small bowl, whisk together egg and milk; set aside. Line two baking sheets with parchment; set aside.Advertisement
On a lightly floured surface, use a 1-inch pastry cutter to make thirty-six rounds. Use the cutter to make indentations on the centers of the rounds without cutting through the dough. Using a pastry brush, coat rounds with egg wash. Cook on prepared baking sheets until raised and golden brown, 10 to 12 minutes.
Transfer to a wire rack to cool. Gently push the indented center into the cavity, and remove to form a shell. If necessary, use a paring knife to coax out the center. Level the bottom with a paring knife so that the shell won't wobble. Repeat with remaining shells.