Prepare box of macaroni and cheese dinner as directed. Add grated Cheddar cheese, 1 can cream of mushroom soup (undiluted) and approximately 1/4 cup milk. Stir well. Place in casserole dish. Sprinkle with small amount of more grated Cheddar cheese. Bake at 300 degrees for 15-30 minutes or until cheese is melted throughout. Note: This is an excellent leftover - tastes great reheated. Serves 6.