In a mixing bowl, combine panko breadcrumbs with milk, ensuring the crumbs are fully saturated. Let this mixture sit for about 10 minutes.

In a large pot, heat olive oil over medium heat. Add finely chopped onions and sauté for 6 to 8 minutes until translucent. Stir in minced garlic and cook for an additional 2 minutes.

Reserve a small amount of the onion and garlic mixture for the meatballs, then add canned tomatoes, kosher salt, and optional fresh basil. Stir well and bring to a gentle simmer for 15 minutes.

In a large bowl, mix the soaked breadcrumbs with eggs. Fold in ground beef, grated Parmesan, chopped parsley, kosher salt, and black pepper gently.

With wet hands, form the meat mixture into 2-inch meatballs, aiming for about 24 meatballs. Place them on a tray lined with parchment paper and chill for 5 minutes.

In a large skillet, heat oil over medium heat. Add the meatballs in batches and brown each side for about 6 to 8 minutes until golden brown.

Transfer the browned meatballs into the simmering tomato sauce. Cover the pot and let them simmer for 20 minutes on low heat.

Taste the sauce and meatballs; adjust seasoning as necessary with salt, pepper, or more fresh basil.