01 - Combine breadcrumbs and milk in a large bowl. Let soak for 2 minutes until absorbed.
02 - Add ground beef, egg, Parmesan, garlic, parsley, salt, and pepper to the breadcrumb mixture. Mix gently until just combined—avoid overmixing to keep meatballs tender.
03 - Form the mixture into 16 equal-sized balls, rolling gently with damp hands to prevent sticking.
04 - Heat 1 tablespoon olive oil in a large skillet over medium heat. Add meatballs in batches, browning on all sides for 5–6 minutes total. Remove and set aside—interior finishing happens in the sauce.
05 - Add the remaining tablespoon olive oil to the same skillet. Sauté onion until soft and translucent, 3–4 minutes.
06 - Stir in minced garlic and cook for 1 minute until fragrant, taking care not to burn.
07 - Pour in crushed tomatoes, oregano, basil, red pepper flakes, sugar, salt, and pepper. Stir to combine and simmer for 5 minutes to meld flavors.
08 - Return meatballs to the skillet, cover, and reduce heat to low. Simmer for 20–25 minutes, turning once halfway through, until meatballs are cooked through and sauce has thickened.
09 - Serve hot over spaghetti or with crusty bread. Top with fresh basil leaves and additional grated Parmesan cheese.