Spanakopita Casserole

1 tablespoon olive oil
1 onion, chopped
3 cloves minced garlic
12 ounces frozen chopped spinach, thawed
¼ cup chopped fresh dill (or mint)
¼ cup chopped fresh parsley
sea or kosher salt and black pepper
4 large eggs
1 cup crumbled feta cheese
1 cup ricotta cheese
20 sheets of phyllo dough, thawed to room temperature
12 tablespoons melted butter, plus more if needed

Preheat the oven to 350° degrees F. Butter a 9x13-inch pan.
In a small frying pan heat the oil over medium-low heat.
Add the onion and garlic, cook until softened, stirring often about 6 minutes.
Remove from heat and stir in the dill and parsley.
Squeeze the water out of the spinach in a colander, or in batches using a ricer or by twisting it up in a clean kitchen towel.
In a large mixing bowl whisk the eggs, feta and ricotta cheese together.
Fold in the onion mixture, spinach, ½ teaspoon salt and ¼ teaspoon black pepper.
Unroll the phyllo sheets and cover them with a damp paper towel.
Take out 5 phyllo sheets and lay it in the bottom of the pan - if the ends hang over the edge that's ok.
Use a pastry brush to coat with butter from edge to edge.
Put in 5 phyllo sheets.
Scoop the spinach filling into the pan and spread evenly from edge to edge.
Fold the edges of the pyhllo dough over the filling.
Repeat the phyllo dough as was done above.
Tuck the edges into the side of the pan if possible or trim the excess off with a sharp paring knife and discard.
Butter the top sheet with the last of the butter.
Score through the top layer of phyllo with a paring knife cutting it into squares so it will be easy to cut once cooked.
Bake 35 - 40 minutes until deep golden brown on top.
Let it sit 5-10 minutes.
Cut it into squares along the score marks.

Note
You can substitute fresh spinach - you will need 2 pounds.
Use a large frying pan to saute the onion and garlic with an extra tablespoon of olive oil - once the onion is soft add the spinach and cook until wilted. Let cool and use in place of the frozen.