Step 1: Prepare the Filling

1. Heat olive oil in a skillet over medium heat.
2. Add chopped onions and sauté until translucent.
3. Add minced garlic and cook for 1-2 minutes until fragrant.
4. Add chopped spinach and cook until wilted. Remove from heat and let it cool.
5. In a mixing bowl, combine the cooked spinach mixture, feta cheese, ricotta cheese, Parmesan cheese, salt, pepper, and chili flakes. Mix well.

Step 2: Prepare the Pastry

1. Thaw the puff pastry sheets according to package instructions.
2. Roll out the pastry sheets lightly on a floured surface.
3. Cut each sheet into equal squares or rectangles (about 4×4 inches).

Step 3: Assemble the Pastries

1. Place a spoonful of the spinach filling in the center of each pastry square.
2. Fold the pastry over the filling to form a triangle or rectangle.
3. Use a fork to press and seal the edges.

Step 4: Bake the Pastries

1. Preheat your oven to 400°F (200°C).
2. Line a baking sheet with parchment paper.
3. Arrange the stuffed pastries on the baking sheet.
4. Whisk the egg with water to make an egg wash. Brush the pastries lightly with the egg wash.
5. Bake for 15-20 minutes or until golden brown and flaky.

Step 5: Serve and Enjoy

1. Remove the pastries from the oven and let them cool for 5 minutes.
2. Serve warm with a side of yogurt dip or your favorite sauce.