Preheat the oven to 375 degrees.
In a nonstick pan on medium heat. Brown the sausage, breaking it up into smaller pieces using a spatula until it is no longer pink. Remove with a slotted spoon into a bowl and set aside, leaving the leftover grease in the pan.
Add the spinach to the pan and saute until it is wilted, season with salt and pepper. Remove from the heat and drain any excess liquid in a strainer. Allow it to cool and squeeze out as much moisture as you can.
In a bowl whisk the ricotta, eggs, parmesan cheese, and mozzarella until smooth. Mix in the sausage and spinach. Season with salt and pepper, mix together well.
Pour the mixture evenly into one pie crust about 3/4 of the way. Remove the other pie crust from the tin and place it on top. Cut off any excess and crimp the edges of the pie crusts together using your fingers or a fork.
Using a fork, gently poke 6 - 8 evenly spaced holes in the top of the crust for ventilation.
Bake in the oven for approximately 40 minutes until the crust is golden brown and a toothpick inserted into the center comes out clean.
Remove from the oven and let sit so the pie can set up for 15 minutes before cutting into portions and serving.