1. Combine ground meat, milk, breadcrumbs, egg, and seasonings in a large mixing bowl. Mix until all ingredients are incorporated.
2. Roll into 1 1/2 inch balls and place on a large rimmed baking sheet.
3. Broil on high 5 minutes on each side to brown, then transfer meatballs to a slow cooker.
4. Pour sauce over meatballs; cover and heat on low 2 to 3 hours.
5. Serve as an appetizer or as part of a main dish.