I got this off a message board awhile back and never tried it, will try it this week.
2-3 lbs potatoes, peeled & cubed
1/2 onion, chopped
chicken broth (about 4 cups)
salt & pepper to taste
1-2 c milk
2 c cheddar cheese, grated
Cube potatoes, place in crockpot with onion, salt & pepper. Add broth to cover. Cook on high 4 hrs till potatoes are cooked through. Blend 1/2 potatoes till smooth. Return to crockpot. Leave on low until dinner time (if needed) Right before serving, stir in milk & cheese. The potatoes should be hot enough to heat the milk & cheese right away. Serve.