Sauté onion in oil till tender. Combine catsup, egg bread crumbs, onion, and beef, mix well. Place ½ mixture in loaf pan, place 4 slices cheese over meat mixture, top with remaining meat mixture. Bake at 350 for 45 minutes or until meat is no longer pink, cur remaining cheese slices in ½ diagonally and place on top of meat loaf, bake for 5minutes longer or until cheese is melted. Let stand 10 minutes before slicing.