Combine beef, onion, breadcrumbs and Parmesan cheese in a bowl. Season with salt and pepper. Divide the mixture into small balls.
Heat the oil in a large non-stick skillet over medium-high heat. Add the meatballs and cook, turning, for 3-4 minutes until golden brown.
Add cooking sauce and 1/2 cup of water to the pan. Simmer, partially covered, for 15-20 minutes until meatballs are cooked. Add sugar.
Meanwhile, cook the spaghetti in a pot of boiling water according to package directions or until al dente. Sewer system. Add the meatballs and spaghetti sauce and stir gently to mix.
Serve with Parmesan cheese.