Take the puff pastry out of the fridge at least 10 minutes in advance so it warms up and you can unroll it easily.
Pour the frozen spinach in a pot with 1 cm of water, cover and bring to boil.
When the ice starts to melt, uncover, bring the heat to medium and cook for about 2-3 minutes.
Add the garlic cloves cut in halves, drizzle with olive oil and season with salt, pepper and ground nutmeg.
Keep them on medium heat until the water all evaporates (careful not to keep them too much on the fire or they'll stick to the bottom of the pot).
When they are done, remove the garlic and set them aside in a bowl and let the cool down completely. (about 20 minutes)
When they are completely cooled, add the ricotta cheese, the Parmesan cheese and if necessary season again with salt, pepper and nutmeg.
Mix well with a fork until the greens and cheese are completely merged together.
Cover the pan with parchment paper and then cover the bottom with a sheet of puff pastry (if you do the small portions, you should be able to cover the bottom with part of the rectangular sheet and also cut out the lid with the leftover pastry).
Make several punches on the bottom with the fork then pour the filling in. Even it out then make holes in the filling to make space for the eggs.
Put the eggs in a pot with cold water and bring to boil, then boil them for about 3-4 minutes; immediately transfer them into cold water to stop cooking and gently peel them.
Place them in the pie and cover with a thin layer of filling to even it up.
Now cover the pie with the other sheet of puff pastry as a lid. Punch it again with the fork so the steam can come out and brush gently with milk so give it a nice golden finish.
Bake it in the oven at 190°C (375°F) for 25 minutes (for the 13cm pie) or 45 minutes (for the 24cm pie).
Serve warm, tepid, or cold! :)