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 1/2 cup cheese. Spoon into 2 quart casserole. Sprinkle remaining cheese on top. Bake at 350~ for 30 minutes.