Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.

In a large skillet, heat olive oil over medium heat, then add chopped onion and sauté for 5 minutes until translucent.

Add minced garlic and stir for 1 minute, then add spinach and wilt for about 3 minutes.

Combine sautéed spinach mixture with ricotta, Parmesan, garlic powder, salt, and pepper in a bowl and mix thoroughly.

Roll out the thawed puff pastry, and cut it into squares about 4 inches wide.

Place a spoonful of filling on each square, fold to create a triangle, and seal the edges with a fork.

Brush tops with beaten egg, space pastries on the baking sheet, and bake for 15-20 minutes until golden brown.

Let the pastries cool slightly before serving warm with a salad or dipping sauce.