Step 1: Preheat the Oven

Start by preheating your oven to 375°F (190°C) and line a baking sheet with parchment paper. This ensures the pastries won’t stick to the surface while baking.

Step 2: Prepare the Spinach Mixture

In a frying pan, heat the olive oil over medium heat. Add the chopped onions and garlic, and sauté them until they turn soft and golden brown. Then, add the spinach to the pan, and cook until it wilts down completely. Season with salt and pepper to taste. Once done, remove from heat and let it cool slightly.

Step 3: Mix the Filling

In a mixing bowl, combine the sautéed spinach mixture with ricotta cheese and crumbled feta cheese. Stir everything together until the filling is well-mixed. Taste and adjust seasoning if necessary.

Step 4: Prepare the Pastry Dough

Roll out the puff pastry sheets on a lightly floured surface. Cut the dough into squares or rectangles (depending on your preferred shape for the pastry). The size should be large enough to hold a generous spoonful of the spinach filling.

Step 5: Stuff the Pastry

Place a spoonful of the spinach filling in the center of each pastry square. Fold the pastry over the filling, forming a pocket or triangle shape. Use a fork to press the edges of the pastry together, sealing the filling inside.

Step 6: Brush with Egg Wash

In a small bowl, whisk together the egg and water to make an egg wash. Brush the egg wash over the top of each pastry to give it a golden, shiny finish when baked.

Step 7: Bake the Pastries

Place the prepared pastries on the lined baking sheet and bake them in the preheated oven for 20-25 minutes, or until they are golden brown and puffed up. Keep an eye on them to avoid over-baking.

Step 8: Serve and Enjoy

Once baked, remove the pastries from the oven and allow them to cool slightly. Serve warm with a dipping sauce of your choice or enjoy them on their own.