To make this recipe gluten free, verify that the breakfast sausage, frozen hash browns, cottage cheese, shredded Pepper Jack cheese, and canned jalapeños are certified gluten free or free from cross-contact concerns, as some packaged brands may contain additives. Also ensure that the nonstick cooking spray and any seasonings used are gluten free. If preparing the casserole in a shared kitchen, use clean cookware, utensils, and work surfaces to avoid gluten contamination.