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).

Lay out a sheet of phyllo dough and brush it with melted butter. Layer another sheet on top and brush again. Cut into squares.

Place a spoonful of the spinach filling in the center of each square. Fold the corners over the filling and pinch to seal.

Place the assembled bites on a baking sheet. Brush the tops with more melted butter.

Bake in the preheated oven for 15-20 minutes, or until golden brown.