01 - Combine breadcrumbs and milk in a large bowl. Allow to soak for 2 minutes until absorbed.
02 - Add ground beef, egg, Parmesan, garlic, parsley, salt, and pepper to the bowl. Mix gently until just combined—avoid overmixing to maintain tenderness.
03 - Form the mixture into 16 equal-sized balls, approximately 1.5 inches in diameter.
04 - Heat 1 tablespoon olive oil in a large skillet over medium heat. Add meatballs in batches, cooking until browned on all sides, about 5–6 minutes total. Remove and set aside—interior does not need to be fully cooked.
05 - Add remaining tablespoon of olive oil to the same skillet. Cook onion until softened and translucent, 3–4 minutes.
06 - Stir in minced garlic and cook for 1 minute until fragrant, taking care not to burn.
07 - Add crushed tomatoes, oregano, basil, red pepper flakes, sugar, salt, and pepper. Stir well to combine and simmer for 5 minutes.
08 - Return browned meatballs to the sauce, cover, and reduce heat to low. Simmer for 20–25 minutes, turning once halfway through, until meatballs are fully cooked and sauce has thickened.
09 - Plate over spaghetti, garnish with fresh basil and additional Parmesan, or serve alongside crusty bread for dipping.