Instructions

1. Remove the frozen filo and spinach out of the freezer and put them in the fridge to defrost for 24 hours.
2. About 2 hours before you get going, move it to the countertop to reach room temperature as it's easier to work with it when soft and more flexible.
3. If you inadvertently missed doing this the day before, you can warm the frozen spinach in a pan on the stove (right before you make the dish) until it's fully thawed. 
4. Preheat the oven to 350F / 180C. 
5. In a large pan, sauté the diced onion until soft and translucent.
6. Add the garlic and let it cook for 1 minute until fragrant. 
7. While the onions are cooking, drain the spinach.
8. Put the thawed spinach into a piece of cheesecloth or a thin dish towel, twist it into a ball to seal, and squeeze any remaining water out. You want the spinach to be as dry as possible.
9. It is vital and very important to drain the spinach extremely or you will end up with a mushy and very wet pie from excess water.
10. In a mixing bowl, add the cooked onions and garlic, drained spinach, almond ricotta, lemon zest, chopped parsley, nutmeg, and black pepper.
11. Mix and combine all the ingredients.
12. Taste the filling and add salt to taste if necessary. 
13. Take the thawed and soft filo dough out of the package and place a slightly damp dishtowel over it to prevent it from drying out.
14. Only open the filo box/package when you are ready to work with it, as it will also help that it does not dry out.
15. Lightly brush the bottom of a large casserole dish with olive oil and add 2 layers of filo dough at a time (you need 12 layers of filo dough in total for the bottom), and then lightly brush some olive oil on the even-numbered sheets.
16. I prefer to let the filo hang over the edge of the casserole dish as this will help
    to fold them over the filling once done.
17. Add the spinach filling and lightly smooth the filling over the base.
18. Now add the remaining filo dough 2 by 2 and brush the even-numbered layers with oil. 
19. Keep one sheet for the top aside.
20. Fold in the overhanging rims over the filling and brush the corners and the layers as needed with olive oil as this will help them to get crispy.
21. Once done take the one sheet you kept aside the last filo sheet, and place it over the top to neatly cover the uneven edges you recently folded and tucked in to make a neat top.
22. Score the pie by using a big and sharp knife, but only cut through the top layers of filo.  Depending on how big you want the cubes, you can do 12 or 18 blocks. 
23. I prefer smaller so cut it into 18 blocks (3 in the width and 6 in the length).
24. You will find it way easier to cut the filo before baking than when it's crispy.
25. Bake at 350F / 180C for 45-50 minutes or until the top filo sheets turned lightly brown and crispy.
26. Remove it from the oven and let it rest for a few minutes before removing slices from the pan as you want it to cool off slightly as it's easier to then take it out and serve. 
27. Store leftovers in an airtight container in the fridge for 2-3 days. That's if you're lucky to have any leftovers.