Preheat oven to 400˚F.
In a large mixing bowl combine bread cubes and milk; let stand 5 minutes, or until the bread has absorbed all the milk.
Using two forks, shred the bread into tiny pieces and add grated onions, egg, garlic, beef, pork, Italian seasoning, salt, and pepper; mix it all together until thoroughly incorporated.
Chill mixture for 15 minutes so it’s easier to roll the meatballs.
Form the mixture into 18 to 24 meatballs, they should be about the size of a ping pong ball.
Arrange the meatballs in a baking dish.
Bake for 18 to 20 minutes, or until the meatballs are cooked through.
Remove from oven.
Add marinara sauce over the meatballs.
Top with shredded mozzarella.
Bake for an additional 6 to 8 minutes, or until sauce is heated through and cheese is melted.
Garnish with chopped fresh parsley.