Cream of Leek Soup

1 lb. leeks
1/2 lb. butter
1 c. flour
1 qt. chicken stock or 4 bouillon
cubes
1 qt. half and half
1 tsp. salt
1/4 tsp. pepper
Clean leeks and cut into 1/2" pieces. Steam in 1/2 cup water
until tender. Do not drain. Set aside. Melt butter in saucepan.
Add flour to make a roux. Cook 2 to 4 minutes. Add chicken stock,
stirring with wire whip, bring to boil. Turn heat on low and add
remaining ingredients. Do not boil. Add 1 cup diced, cooked
potatoes and 1 cup diced, cooked ham, if desired.