Begin by heating the sauce: In a Dutch oven, heat the sauce, covered, and cook on low heat until it warms through.
While the sauce is heating, mix the meatball mixture: In a small skillet, heat the oil on low heat and cook the onion and garlic until they're soft. Move the onions and garlic to a large bowl and stir in the meat, egg, milk, breadcrumbs, salt, pepper, a half cup of the grated parmesan cheese, and the minced herbs. Make 12 round, equal sized meatballs out of the mixture.
Add the meatballs to the sauce, without stirring them. Cover and simmer for thirty minutes, or until the meatballs are cooked through.
Arrange the meatballs in a cast iron skillet, and pour the sauce around the meatballs. Top with the mozzarella and the rest of the Parmesan and broil the pan just until the cheese melts. This will take just a few minutes. Add the basil and serve with crusty bread.