This is a favorite from my childhood.
Cook pasta in boiling water. Be sure to occasionally stir the macaroni so it won’t stick. Saute onions, pepper, and beef. The beef will be done first, drop the temperature on the burner to low or simmer, add the cheese to the ground beef, and stir it in to completely melt. Drain the macaroni when done, add the now cheesy beef and the tomato soup to the macaroni, mix in well.