Wash the spinach, shop into stripes and place it in a pot with boiling water. Cook for around 10 minutes then drain the water and set the spinach aside.

Clean and chop the onion into small pieces. Melt the butter in a medium sized pan and add the onion in the pan. Fry until it gets a nice brown color and leave it aside to cool for a few minutes.

In a big bowl, make the filling by combining the spinach, already fried onion, ricotta cheese, feta cheese, salt, black pepper, and nutmeg. Use a spoon to stir and combine everything.

Now place the puff pastry on your working surface, roll it a few times if needed and start cutting circles using a bigger glass or a mold. For one pie you will need one smaller and one bigger circle so cut big circles as much as you have small.

Brush the muffin mold with olive oil. First place the bigger circles in the mold, then add a tablespoon or two of the filling in the middle, place the smaller circles on top of the muffins and seal them with a form on the ends. Repeat the same procedure for all the pies.

Make the egg wash by combining the egg and the water. Brush the pies and bake at 390°F (200°C) for around 20 minutes or until they get golden color.