Cut the white bread into small cubes and combine with the milk in a small bowl.
Place the ground turkey in a large bowl. Grind the bacon, garlic and onions to a fine paste in a food processor, and then mix into the turkey. Squeeze the excess milk from the bread and add to the turkey along with spinach, Parmesan, parsley, salt, pepper, nutmeg and egg. Mix gently but thoroughly, and then refrigerate 1 hour.
Shape the mixture into 1 1/2 to 2-inch meatballs. Heat the olive oil in large saute pan until hot but not smoking and brown the meatballs on all sides, about 10 minutes. Heat the tomato sauce to a low boil in a large deep skillet, and then add in the meatballs once they have been evenly browned. Reduce the heat and simmer, an additional 15 to 20 minutes.
Serve over pasta with grated Parmesan or on toasted roll with mozzarella cheese.