Preparation Preheat oven to 350°F. Unfold pie crust. Press out fold lines; if crust cracks, wet fingers and push edges together to seal. Sprinkle flour over crust. Place crust floured side down in 9-inch-diameter glass or ceramic pie dish. Fold edge under and crimp decoratively. Melt butter in heavy large skillet over medium heat. Add onion and sauté until tender, about 8 minutes. Mix in spinach, salt, pepper and nutmeg. Sauté until all liquid from spinach evaporates, about 3 minutes. Combine ricotta, mozzarella and Parmesan cheeses in large bowl. Mix in eggs. Add spinach mixture; blend well. Spoon cheese mixture into pie crust. Bake until filling is set in center and brown on top, about 40 minutes. Let stand 10 minutes. Cut pie into wedges.
Preparation Preheat oven to 350°F. Unfold pie crust. Press out fold lines; if crust cracks, wet fingers and push edges together to seal. Sprinkle flour over crust. Place crust floured side down in 9-inch-diameter glass or ceramic pie dish. Fold edge under and crimp decoratively. Melt butter in heavy large skillet over medium heat. Add onion and sauté until tender, about 8 minutes. Mix in spinach, salt, pepper and nutmeg. Sauté until all liquid from spinach evaporates, about 3 minutes. Combine ricotta, mozzarella and Parmesan cheeses in large bowl. Mix in eggs. Add spinach mixture; blend well. Spoon cheese mixture into pie crust. Bake until filling is set in center and brown on top, about 40 minutes. Let stand 10 minutes. Cut pie into wedges.