In a large skillet cook ground beef and onion over medium-high heat until meat is brown, using a wooden spoon to break up meat as it cooks. Drain off fat.
Stir in beans, tomatoes, tomato sauce, macaroni, green chile peppers, chili powder, and garlic salt. Bring to boiling; reduce heat. Simmer, covered, about 20 minutes or until macaroni is tender but still firm, stirring frequently. Remove from heat.
Sprinkle meat mixture with cheese. Cover and let stand about 2 minutes or until cheese is melted.