Place bread in a medium bowl and pour the milk over the bread. Allow the bread to sit for about 5 minutes to allow the milk to soak into the bread.
By hand, mix together the bread, onion, eggs, garlic, salt, nutmeg, and pepper in a bowl until combined. Add the ground beef and pork and mix till just combined.
Preheat oven to 400°F and line a baking sheet with parchment paper or a slip mat.
Roll the meat into 24 meatballs and place on the baking sheet.
Bake for 15 minutes, until the meatballs become browned on the outside.
Place meatballs in slow cooker, and prepare the sauce.