Prepare potatoes according to directions on box. Set aside.
In a large skillet, saute ground beef over medium heat for 1 minute. Add onion to skillet and continue to cook until beef is no longer pink and onion is beginning to brown. Drain off some of grease if desired.
Add corn, green beans, and gravy to skillet. Mix thoroughly. Add salt and pepper to taste. Pour mixture into a 9x13 inch baking dish. Spread potatoes over top. Lay cheese slices over potatoes.
Bake in preheated oven for 40 minutes, until cheese turns golden brown.