De-Lightful Tuna Casserole

Cook macaroni according to package directions. Meanwhile, in a large bowl, combine the soup, mushrooms, cheese, milk, tuna, pimientos, onion, mustard and salt. Drain macaroni; add to tuna mixture and mix well. , Transfer to a 2-qt. baking dish coated with cooking spray. Sprinkle with cornflakes. Bake, uncovered, at 350° for 25-30 minutes or until bubbly.