In a large pot or dutch oven on medium-high heat, break apart and cook ground beef and onions until the beef is no longer pink and onions translucent. Drain off excess grease.
To the pot, add the chili beans kidney beans, tomato purée, 2 cups of water, chili powder, salt, and sugar. Bring to a boil.
Add the broken spaghetti and cook until al dente, stirring periodically. Taste and adjust seasonings as desired. Add 1-3 cups water to desired chili texture.
Ladle and serve. If reheating, add additional water or tomato puree as needed. To create that lunch school memory, complete the lunch tray with a bowl of chili, crackers, grilled cheese or peanut butter and syrup sandwich, carrots and celery sticks, a no-bake cookie or cinnamon roll, and milk.