Begin by preheating your oven to 375°F (190°C) to ensure it's ready for baking.
In a medium mixing bowl, thoroughly combine the softened cream cheese, finely chopped spinach, shredded mozzarella, and grated Parmesan.
Add the garlic powder, onion powder, and season with salt and pepper. Stir the mixture until all the seasonings are evenly distributed.
Lightly flour your work surface and roll out the puff pastry sheets until they’re about 1/8 inch thick. Cut each sheet into squares measuring approximately 3x3 inches.
Take about 1 tablespoon of the cheesy spinach mixture and place it in the center of each pastry square.
Carefully fold the corners of the pastry over the filling to create a pocket, ensuring to pinch and seal the edges tightly.
Using a pastry brush, gently apply the beaten egg to the top of each pastry pocket.
Arrange the filled pastry bites on a parchment-lined baking sheet, making sure they are spaced apart.
Bake in the preheated oven for 20-25 minutes, or until the bites are puffy and golden brown.
Once baked, remove the bites from the oven and let them cool slightly on the baking sheet before transferring to a serving plate.
Notes
For a beautiful presentation, serve on a rustic wooden platter and garnish with fresh herbs.