Combine the first six ingredients; crumble beef over mixture and mix well. Press into an ungreased 9-in. square baking pan. Bake at 375° for 25 minutes or until a thermometer reaches 160°; drain.
Combine the potatoes, corn, beans, onions and 1/2 cup of cheese; spread over meat loaf. Sprinkle with the remaining cheese. Bake 15 minutes longer or until the potato layer is lightly browned and heated through.