Make sure that the apple strudel filling has fully cool down. Cut 6 to 7 even circles out of the puff pastry sheet using a glass, a cup or a serving ring. Then scoop a dollop of the cooked apple strudel filling in the middle. Beat the egg in a cup and brush the pastry lightly with it.
Bake the apple pocket pies in a preheated oven at 400°F (200°C) for 20 to 25 minutes until golden. Then remove the apple pocket pies from the hot oven. Serve warm or lukewarm.