Preheat your oven to 400°F. Line a baking sheet with parchment paper.
On a lightly floured surface, roll out each sheet of puff pastry to smooth out creases. Cut each sheet into 9 equal squares.
In a bowl, combine the pepperoni, mozzarella cheese, oregano, basil, garlic powder, and red pepper flakes. Mix well.
Place about 2 tablespoons of the pepperoni mixture in the center of each pastry square. Fold the corners of the pastry over the filling to create a pocket and pinch the edges to seal tightly.
Transfer the filled rolls to the prepared baking sheet. Brush the tops with the beaten egg for a golden finish.
Bake in the preheated oven for 15-20 minutes, or until the rolls are puffed and golden brown. Allow to cool for a few minutes before serving.