Line a baking sheet with foil.
In a bowl, combine bread and milk. Mash together and soak for about 10 minutes or until bread is moistened and paste like.
In a bowl, whisk together egg, garlic, salt, and pepper.
In a large bowl, combine ground beef and ground pork and gently break up to chunks.
Add bread, egg mixture, Reggiano cheese, onions, Italian parsley, and fennel seeds. Gently mix together until just combined. DO NOT OVER HANDLE AND OVER MIX.
Using a scoop, portion meat mixture. With lightly oiled hands, shape meat into the size of a golf ball by rolling between the palm of hands.
Arrange meatballs in a single layer on prepared baking sheet.
Bake meatballs in a 425 F oven for about 10-15 minutes or until internal temperature of 160 F is reached.
Remove from pan and keep warm. Serve with marinara, BBQ or sweet and sour sauce.