Cook spaghetti according to instructions, heat chili w/beans on stove top; warm ketchup in microwave. Chop onion.
Prepare plates: add spaghetti to plate and spoon warmed ketchup onto spaghetti then add some chili w/beans. Garnish with about a tablespoon of chopped onions or more if desired. Add parmesan cheese according to taste. I also add a little pepper to mine....can also be served with crackers of choice.