In a medium bowl, soak the breadcrumbs in the milk.
Add the beef, garlic, parsley, Parmesan cheese, egg and 1 tsp salt to the soaked breadcrumbs and stir with a fork until combined.
Place about 2 tablespoons of mixture in your hand and press a mozzarella cube into the center. Shape the meat around the cheese, forming a ball. Repeat with remaining mozzarella.