Set the slow cooker on high. Add the tomato sauce.

In a large bowl, mix together the ground turkey, egg, breadcrumbs, cheese, seasoning, garlic powder, onion powder, milk, salt, and pepper together. Mix well with your hands until well combined.

Roll into balls about 3 tablespoons in size. Place the meatballs in the slow cooker.

Once all the meatballs are in the slow cooker, turn the slow cooker down to low.

Cook for 8 hours on low, or until the meatballs are cooked through. (You can also cook on high for 4 hours if you need to speed things up).