Heat oil in a large saucepan over medium heat. Add onion and garlic and sauté, stirring frequently until lightly softened, 2 to 3 min. Stir in hot pepper flakes and sugar, cooking for 10 to 20 sec. Add tomato paste, diced tomatoes, basil, oregano, broth and meatballs; bring to a boil. Reduce heat and simmer 10 to 15 min.
Meanwhile, cook pasta according to package directions; drain and keep warm. Gently stir pasta and parsley into sauce. Garnish each serving with Parmesan cheese.