• 1 pound italian sausage
• 1/2 medium yellow onion, diced
• 1 medium green bell pepper, diced
• 1 cup sliced button mushrooms
• 1 cup pizza sauce or marinara
• 1/2 cup sliced black olives
• 3 cups grated mozzarella cheese, divided
• 1 unbaked roll-out pie crust, store-bought or homemade