In large skillet, add oil, and onion. Saute until tender. Add ground beef. Stir to brown. Drain off fat. Add mushrooms, corn and soup. Mix well. Season to taste. Cook noodles in salted water; drain. Mix noodles, meat and half cup cheese. Spoon into 2 litre casserole. Sprinkle remaining cheese on top. Bake at 180ºC for 30 minutes.