Preheat oven to 350°F. Mix ground beef, ground pork, eggs, onion, bread crumbs, garlic, salt, and desired amount of Italian blend herb grinder in large bowl until well blended. Shape into 12 meatballs.
Press 1 mozzarella cheese cube into the center of each meatball, forming meatball around the cheese to completely enclose it. Place in 13x9-inch baking dish. Pour sauce over meatballs. Twist Italian blend herb grinder over meatballs.
Bake 30 to 45 minutes or until meat is cooked through. Serve meatballs on slider rolls with additional Italian blend herb grinder. Sprinkle with Parmesan cheese, if desired.