To give this Pizza Casserole a gluten-free twist just replace the regular penne pasta with your preferred gluten-free penne or pasta alternative. Make sure that all the other ingredients, such, as seasoning, crushed tomatoes and toppings like pepperoni are certified gluten-free. This will allow you to relish every cheesy and savory mouthful of this comforting casserole without any concerns about related sensitivities. It's a variation, on a favorite that can be enjoyed by everyone!