Place beef, egg, onion, bread crumbs, Parmesan, milk, garlic, Worcestershire, mustard, hot sauce, salt, pepper and garlic salt into a large mixing bowl, stirring until just combined. Take 1/4 cup beef mixture and press into center with your thumb to make room for cheese ball. Place cheese in middle then with hands enclose the cheese with the beef, making sure the cheese is completely covered. Place meatballs into prepared baking dish and bake for 30 to 35 minutes, until cooked through.