Saute hamburger until lightly browned. Add onion but do not brown. Add salt, chili powder and tomato sauce. Stir together; simmer for about 15 minutes. Cook macaroni according to package directions; stir into meat mixture. Place in large casserole dish. Mix soup and milk and pour over noodle and meat mixture. Top with cheese. Bake for 30 minutes in 350° oven or about 15-20 minutes on high in microwave.

This makes a huge amount. You will need to half this or use 2 pans unless you've got one that is big enough.