1/2 c. butter
3 lg. leeks, finely chopped (including tops)
1 stalk celery, finely chopped
4 c. water
4 c. chicken broth
2 lbs. potatoes, peeled and diced
2 tsp. salt
1/2 tsp. white pepper
1/2 c. heavy cream or half and half

Melt 1/4 cup of the butter in a kettle; add leeks and celery. Reduce heat, cover, and cook for 5 minutes or until the vegetables "sweat"; do not fry. Add water, chicken broth, potatoes, salt, and pepper and simmer 45 minutes or until leeks and potatoes are very soft.

Puree vegetable mixture in a blender or food processor and return to kettle. If too thick, add more chicken broth. Just before serving, add remaining 1/4 cup butter and cream. Heat through.