Prepare the pie crust the night before to save time (or use pre-made crust like I did).
Preheat oven to 350℉ and drain spinach in a colander while you prepare the other ingredients.
Roll out chilled pie dough and carefully place into a 9-inch pie dish. Cut and discard any overhang of the crust.
Pre-bake the pie crust for 8 minutes (step can be skipped if you bought pre-made crust).
Whisk together the eggs, milk, and parmesan cheese until combined. Sprinkle with salt and pepper.
Blot and squeeze any water out of spinach. Remove the pie crust from the oven and spread the spinach on top.
Pour the egg mixture over the spinach. Sprinkle shredded cheese on top.
Bake the quiche until it is golden brown on top and the center is no longer jiggly. Baking can take anywhere between 45 minutes - 1 hour. (Allow 5 minutes for the quiche to cool before slicing and serving)