6 leeks
2 medium-size onions
½ cup butter
2 quarts strained chicken broth
¾ pound diced potatoes
Salt-Pepper
½ cup unsalted butter
1 cup cream
¼ cup chopped chives

Clean leeks. 

Chop leeks and onions and simmer slowly in butter, taking care that they do not brown. 

As soon as vegetables are soft, add chicken broth and potatoes. 

Season to taste with salt and pepper and cook gently until potatoes are soft. 

Press through a sieve. 

Add unsalted butter and cream and heat over hot water. 

Chill in the refrigerator. 

Serve with a sprinkling of finely chopped chives.