1.Place broth, skim milk, onion, two potatoes, and rosemary into the Vitamix container and secure lid.
2.Select Variable 1.
3.Turn machine on and slowly increase speed to Variable 10, then to High.
4.Blend for 4-5 minutes or until heavy steam escapes from the vented lid.
5.Reduce speed to Variable 3 and remove the lid plug.
6.Add spinach and reserved potato through the lid plug opening and blend until potato is chopped, about 10 seconds.
7.Drop in chicken and blend for an additional 5 seconds.
For recipe variation, use vegetable bouillon cubes and omit chicken stock to make this recipe suitable for vegetarian diets.