Cook macaroni until tender. Mix other ingredients, except potato chips. Pour 1/2 mixture in casserole dish and crumble 1/2 potato ... minutes or until bubbly.
Saute onion in the butter; stir in the soup, milk and mix well. Break tuna in chunks. Mix all this ... in a greased casserole dish. Top with crushed potato chips. Bake at 350 degrees for 30 minutes.