Preheat your oven to 400°F (200°C).

Mix the filling by combining the chopped spinach, ricotta cheese, mozzarella cheese, Parmesan cheese, garlic powder, onion powder, salt, and pepper in a large bowl.

Roll out the puff pastry sheet on a lightly floured surface and cut it into squares, approximately 4x4 inches.

Spoon a generous amount of the spinach mixture onto the center of each pastry square.

Fold the corners of the pastry over the filling to create a pocket, pressing and sealing the edges firmly.

Arrange the puffs on a lined baking sheet and brush the tops with the remaining beaten egg.

Bake for 20-25 minutes or until the puffs are puffed up and golden brown.