1. Preheat oven to 400°F (200°C).

2. Heat olive oil in a skillet over medium heat.

3. Add chopped onion and sauté until translucent, about 2–3 minutes.

4. Add minced garlic and cook until fragrant, about 30 seconds.

5. Stir in spinach and cook until wilted, about 2–3 minutes.

6. Transfer spinach mixture to a fine mesh strainer and press to remove excess liquid.

7. In a bowl, combine drained spinach, crumbled feta, parsley, ricotta, salt, and pepper.

8. Lightly flour a work surface and roll puff pastry into an 1/8-inch thick rectangle.

9. Cut pastry into 4×4 inch squares.

10. Place a spoonful of filling in the center of each square.

11. Fold squares into triangles and seal edges with a fork.

12. Cut a small slit on top of each pastry to vent.

13. Brush pastries with beaten egg.

14. Chill pastries in refrigerator for 10 minutes.

15. Bake on a parchment-lined tray for 18–22 minutes until golden brown.

16. Transfer to a cooling rack for 5 minutes before serving.