This tuna casserole recipe is creamy, delicious, and gluten-freefinally, classic comfort food for those on gluten-restrictive diets. Use your favorite gluten-free pasta shape: rigatoni, macaroni, or shells produce very good results. Also, for convenience or to save the time involved in making your own gluten-free cream of mushroom soup, use canned cream of mushroom soup that is not condensed and does not require dilution.