01 - In a large bowl, combine ground beef, breadcrumbs, Parmesan cheese, egg, minced garlic, milk, salt, black pepper, and basil. Mix gently until just combined — avoid overmixing to keep meatballs tender.
02 - Form the mixture into golf ball–sized meatballs, yielding approximately 16 portions. Place on a plate or tray and set aside.
03 - Heat 2 tbsp olive oil in a large skillet over medium heat. Add meatballs and cook, turning frequently, until evenly browned on all sides, about 6 minutes. Remove 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 minced garlic and cook for 30 seconds until fragrant.
05 - Pour in the crushed tomatoes and broth. Stir in salt, pepper, and sugar if using. Bring to a simmer and cook for 5 minutes to let flavors meld.
06 - Stir in the heavy cream and 1/4 cup Parmesan cheese until smooth. Add chopped basil and mix well.
07 - Return the browned meatballs to the skillet, nestling them into the sauce. Simmer uncovered on low heat, gently turning the meatballs occasionally, for 15 to 20 minutes until cooked through and the sauce has thickened.
08 - Taste the sauce and adjust seasoning as needed. Garnish with fresh basil leaves and serve over pasta, rice, or alongside crusty bread.