01 - In a large bowl, combine ground beef, breadcrumbs, Parmesan cheese, egg, minced garlic, milk, salt, black pepper, and chopped basil. Mix gently until just combined — avoid overmixing to keep meatballs tender.
02 - Form the mixture into golf ball-sized meatballs, yielding approximately 16 pieces. Place them on a plate or tray as you work.
03 - Heat olive oil in a large skillet over medium heat. Add the meatballs and cook, turning frequently, until browned on all sides, about 6 minutes. Remove from the skillet and set aside — they will finish cooking in the sauce.
04 - In the same skillet, add the chopped onion and sauté until softened, 3 to 4 minutes. Add the garlic and cook for an additional 30 seconds until fragrant.
05 - Pour in the crushed tomatoes and broth. Season with salt, pepper, and sugar if using. Stir to combine and let the sauce simmer for 5 minutes to begin developing flavor.
06 - Stir in the heavy cream and 1/4 cup Parmesan cheese until smooth. Fold in the chopped basil. Nestle the browned meatballs back into the skillet, spooning sauce over them.
07 - Reduce heat to low and simmer uncovered for 15 to 20 minutes, gently turning the meatballs occasionally, until they are cooked through and the sauce has thickened to a creamy consistency.
08 - Taste the sauce and adjust salt and pepper as needed. Garnish with extra fresh basil leaves and serve hot over cooked pasta, rice, or alongside crusty bread.