In a large bowl, combine the ground beef, breadcrumbs, Parmesan cheese, parsley, egg, minced garlic, salt, black pepper, and Italian seasoning. Mix until just combined.

Form the mixture into meatballs, about 1 to 1.5 inches in diameter.

In a large skillet or saucepan, heat the olive oil over medium heat until shimmering.

Carefully add the meatballs to the skillet in batches, and brown them on all sides for about 5–7 minutes. Remove and set aside.

In the same skillet, add the chopped onion and sauté until translucent, about 3–4 minutes.

Mix in the minced garlic and cook for an additional 30 seconds.

Stir in crushed tomatoes, sugar (if using), salt, black pepper, oregano, and basil. Bring to a gentle simmer.

Return the browned meatballs to the skillet, gently nestling them into the sauce.

Cover and simmer for about 20–25 minutes, or until cooked through and the sauce has thickened.

Dish up the meatballs and sauce over pasta, rice, or with crusty bread, garnished with fresh basil if desired.