This recipe is naturally close to gluten free, but it is important to confirm that the shredded cheeses, grated parmesan, garlic powder, onion powder, and any packaged ingredients are certified gluten free, as some brands may contain anti-caking agents or additives with hidden gluten. Use a clean baking dish, utensils, and prep area if cross-contact is a concern. If serving this casserole with other side dishes, choose certified gluten-free options to keep the full meal gluten free.