Grease bottom and side of round pan (8 inch, 20 cm diameter; 3 inch, 7 cm deep) and line bottom with parchment paper. Set aside.
Heat pan over medium heat.Add olive oil and onion. Cook until translucent. Then, add spinach to the pan and cook until wilted.Add salt and pepper to taste. Strain spinach and squeeze out moisture.Then, transfer spinach to a bowl and cut into smaller pieces with scissors. Add Ricotta and Parmesan cheese to bowl. Mix and set aside.
Cover bottom and side of prepared pan with thawed puff pastry sheet. Trim the edges.Then, fill pan with half of the filling. Using a spoon, make 4 holes in the filling and add an egg in each one.
Then, cover with the rest of filling. Spread evenly.
Cover with a second puff pastry sheet. Pinch to seal the edges.
Using a knife, make a slit in the center and brush top with egg wash.
Bake in preheated oven at 425oF (220oC) for 30-40 minutes, until golden brown.
Let it cool down completely.
