Prep: 45 minutes
Baking: 50 minutes
Standing: 10 minutes
Ease pastry into pie plate, being careful not to stretch pastry.
Preheat the oven to 375 degrees F. In a large skillet, cook Italian sausage and onion for 10 to 15 minutes or until sausage is brown and onion is tender. Drain off fat.
In a large bowl, beat together whole eggs and egg white. Stir in drained spinach, mozzarella cheese, ricotta cheese, garlic powder, and the meat mixture. Spread sausage mixture in pastry-lined pie plate. Trim pastry to edge of pie plate.
Place remaining dough on top of filling; trim pastry to 1/2 inch beyond edge of pie plate. Fold top pastry under bottom pastry. Crimp edge as desired. In a small bowl, combine egg yolk and the water; brush top of pastry with egg yolk mixture. Cut slits to allow steam to escape.
Bake pie in the preheated oven for 50 to 55 minutes or until top is golden brown. If necessary to prevent overbrowning, cover edge of pie with foil after 30 minutes of baking. Let stand 10 minutes before serving. Makes 10 servings.