Preheat oven to 450 degrees F (230 degrees C). Press pie crust into a pie plate.
Bake in the preheated oven until slightly brown, about 8 minutes. Remove crust from oven and lower temperature to 350 degrees F (175 degrees C).
Layer eggplant, green onions, Italian seasoning, salt, and pepper in the pie crust, ending with a layer of eggplant. Mix mozzarella cheese, Cheddar cheese, and mayonnaise together in a bowl; spread over eggplant layer. Cover the browned edges of pie crust with thin strips of aluminum foil.
Bake in the preheated oven until cheeses are slightly browned, about 35 minutes.