1. Heat a medium sauce pan over medium low heat. Saute onion in butter until soft, about 5 minutes. Add potatoes, stock, and 1 cup corn. Simmer with lid on until potatoes are tender, about 15 to 20 minutes.
2. Place mixture and milk into the Vitamix container and secure lid.
3. Select Variable 1.
4. Turn machine on and slowly increase speed to Variable 7.
5. Blend for 10 to 15 seconds.
6. Return mixture to saucepan over low heat. Stir in remaining corn and season with salt and pepper. Serve garnished with fresh chopped parsley.