Divide pastry in half. On a lightly floured surface, roll out half of pastry 1/8 inch thick. Using a floured 2 inch round cookie cutter, cut dough into 24 rounds. Transfer rounds to a lightly greased large rimmed baking sheet; set aside.
On a lightly floured surface, roll out remaining half of pastry 1/8 inch thick. Using a floured 2 inch round cookie cutter, cut dough into 24 rounds. Using a floured 1 1/4 inch round cookie cutter, cut out centres from these 24 rounds; reserve centres for another use.
Whisk together egg and water until blended. Brush rounds in pan with egg mixture. Top each of these rounds with a cut round. Cover and freeze for 1 hour. This helps the puff pastry rise when baking.
Meanwhile, preheat oven to 425°F.
Remove pan from freezer and uncover.
Bake until pastry is light golden and puffed, about 12 minutes. Remove shells from pan and cool completely on a rack. Shells may be frozen for up to 1 month. If freezing, layer shells with parchment paper in an airtight container. Thaw before using.
Nutritional analysis per serving
*Ingredient not included in nutritional analysis.
68 calories, 4.2 g fat, 1.5 g protein, 6.5 g carbohydrate, 0.4 g fibre, 59 mg sodium