In a mixing bowl, combine chopped spinach, cream cheese, sour cream, mozzarella cheese, Parmesan cheese, minced garlic, salt, and black pepper. Mix until well combined.

Preheat the oven to 375°F (190°C). Roll out the puff pastry on a floured surface and cut into squares.

Place a spoonful of the spinach filling in the center of each pastry square. Fold the corners over to create a pocket and seal with a fork.

Place the filled pastry bites on a baking sheet and bake for 20 minutes or until golden brown.