Instructions

1. 1
   In a slow cooker, combine potatoes, onions, water, parsley, celery, salt, pepper, chicken broth and butter.
2. 2
   Cook until done -- on low heat, 9 to 11 hours, or on high heat, 3 to 4 hours.
3. 3
   When done, add milk and reheat.
4. 4
   Serve plain or use an immersion blender/put mixture in blender for a smoother soup.
5. 5
   Reheat if necessary.