Step 1: In a large bowl, combine the fresh breadcrumbs and milk. Let stand for 5-10 minutes until the breadcrumbs have softened and absorbed the milk. This is a crucial step for the Best Meatball Recipe's tenderness.
Step 2: Add the ground beef, ground pork, and ground veal to the bowl with the soaked breadcrumbs. Add the grated cheese, chopped parsley, beaten eggs, minced garlic, minced onion, dried oregano, red pepper flakes (if using), salt, and black pepper.
Step 3: Using your hands, gently mix all the ingredients together. Be careful not to overmix, as this can lead to tough meatballs. Mix just until everything is combined.
Step 4: With damp hands, form the mixture into golf-ball-sized meatballs, approximately 1.5 to 2 inches in diameter. You should get about 24-30 meatballs from this Best Meatball Recipe.
Step 5: Heat the olive oil in a large, heavy-bottomed skillet or Dutch oven over medium-high heat. Once hot, carefully place the meatballs into the skillet, ensuring not to overcrowd the pan. You may need to work in batches.
Step 6: Sear the meatballs until beautifully browned on all sides, about 2-3 minutes per side. They don't need to be cooked through at this stage, just nicely caramelized.
Step 7: Once browned, carefully transfer the meatballs directly into your pot of warm marinara sauce. Repeat with any remaining meatballs until all are seared and in the sauce.
Step 8: Bring the sauce and meatballs to a gentle simmer. Cover and cook for at least 30-45 minutes, stirring occasionally, to allow the meatballs to cook through and absorb the flavors of the sauce. For the truly Best Meatball Recipe, let them simmer longer, up to 2 hours, for deeper flavor.
Step 9: Taste and adjust seasoning if necessary. Serve hot with your favorite pasta, on a sub roll, or as an appetizer. Garnish with extra fresh parsley and grated Parmesan cheese.