Preheat your oven to 400°F (200°C) to ensure it reaches the correct temperature while you assemble the pastries. Line a baking sheet with parchment paper and set it aside. This makes for an easy cleanup and prevents the pastries from sticking.

Heat the olive oil in a large skillet over medium heat. Add the finely chopped fresh spinach and cook, stirring occasionally, until wilted, about 2-3 minutes. Remove from the heat and let the spinach cool slightly. I find that letting the spinach cool for a few minutes keeps the ricotta mixture from becoming too runny in the next step.

In a medium bowl, combine the cooked spinach (from Step 2), ricotta cheese, grated Parmesan cheese, garlic powder or minced fresh garlic (whichever you prefer), and salt and black pepper to taste. Mix everything well until you have a creamy, even filling.

On a lightly floured surface, roll out the thawed puff pastry sheets to smooth out any creases. Cut each sheet into 4 equal squares so you have 8 squares in total. This step helps create delicate, flaky layers for the perfect pastry. I like to work quickly so the pastry stays cold and puffs up more beautifully in the oven.

Place a spoonful of the spinach and cheese mixture (from Step 3) in the center of each puff pastry square (from Step 4). Fold each square over to form a rectangle or triangle, depending on your preference. Use a fork to press and seal the edges firmly. This will help prevent any filling from leaking during baking.

Transfer the filled pastries onto the prepared baking sheet. Brush the tops of each pastry with the beaten egg to help them achieve a beautiful golden color as they bake. Place the pastries in the preheated oven and bake for 15-20 minutes, or until they are puffed and golden brown.

Remove the pastries from the oven and let them cool slightly before serving. Enjoy these spinach stuffed pastries warm or at room temperature. Sometimes, I like to sprinkle a little extra Parmesan on top before serving for an added cheesy finish.