Heat a skillet over medium heat and cook the Italian meatballs according to package directions until heated through and lightly browned. Set aside.
In a large saucepan or Dutch oven, cook the ground beef over medium heat for about 5–6 minutes, breaking it apart with a spoon until browned. Drain excess fat if necessary.
Add olive oil to the pot along with diced onion and cook for 4–5 minutes until softened. Stir in garlic and cook for another 30 seconds.
Add crushed tomatoes, tomato sauce, tomato paste, oregano, basil, red pepper flakes, sugar (if using), salt, and pepper. Stir to combine.
Add the cooked meatballs to the sauce. Reduce heat and simmer gently for 20 minutes so the flavors meld together.
Meanwhile, cook spaghetti according to package directions. Drain.
Spoon the sauce and meatballs over pasta and finish with fresh herbs and grated Parmesan cheese.
Tip: Serve with warm garlic bread and a simple green salad for a classic Italian-style family dinner.