To make sure that this Sour Cream Chicken Enchilada Casserole is completely gluten free opt for corn tortillas instead of flour tortillas. Corn tortillas are naturally free of gluten. Add an authentic texture to the dish. Additionally it's important to ensure that all the ingredients used, such as soup and shredded cheese are clearly labeled as gluten free to prevent any cross contamination. By making these adjustments you can confidently relish in the flavors of this casserole without any concerns about gluten. Bon appétit!