In a mixing bowl, combine chopped spinach, ricotta cheese, feta cheese, beaten egg, minced garlic, salt, and black pepper. Mix well until combined.

Set the filling aside.

Preheat the oven to 400°F (200°C).

Roll out the puff pastry on a lightly floured surface to about 1/8 inch thick.

Cut the pastry into squares, approximately 4x4 inches.

Place a spoonful of the spinach filling in the center of each pastry square.

Fold the pastry over to form a triangle and press the edges to seal. Use a fork to crimp the edges for a decorative touch.

Brush the tops with olive oil for a golden finish.

Arrange the puffs on a baking sheet lined with parchment paper.

Bake in the preheated oven for 20-25 minutes or until golden brown.

Remove from the oven and let cool slightly before serving.