Preheat oven to 350 degrees.
Brown ground beef and onion together until beef is cooked an onion is soft.
In the same pot you used to cook the noodles, add the drained noodles, ground beef mixture, corn and cream of mushroom soup. Stir together. Add the cheese and stir.
Pour into casserole dish.
Cover and bake for 50 minutes. If using a small pan (1 qt or less), bake at 325 degrees.
FREEZER DIRECTIONS: Place in foil pans before baking. Cover tightly with foil and freeze. When you are ready to serve, thaw overnight in the fridge. Bake according to directions above, adding 5-10 minutes (depending on pan size, because it will be cold form the fridge).