To make this Cabbage Roll Casserole Recipe gluten free, use a certified gluten-free marinara sauce and verify that the bacon, mozzarella cheese, seasonings, rice, butter, and nonstick cooking spray are gluten free. Rice and cabbage are naturally gluten free, but packaged ingredients should always be checked for gluten-containing additives. Use clean cookware, utensils, and prep surfaces to avoid cross-contact with gluten-containing foods.