Cream of Brie and Leek Soup

1/2 c. butter
8 lg. leeks, finely chopped (white
only)
4 c. (or more) chicken stock
1/2 c. flour
4 c. half & half cream
1 1/2 lbs. Brie cheese, well chilled
and cut into cubes
Salt and pepper to taste
2 tbsp. fresh chives, minced
Melt 1/4 cup of the butter in a soup kettle over medium heat.
Add leeks and saute until translucent, stirring frequently, about 4
minutes. Add stock and bring to a boil. Reduce heat, cover, and
simmer about 25 minutes. Puree mixture in batches in blender. Melt
remaining butter in a saucepan over medium heat. Add flour and stir
2 minutes. Blend in half & half; whisk until smooth. Add cheese in
batches, stirring until cheese melts and mixture is smooth. Strain
through fine sieve. Return to saucepan. Add leek puree and heat
through. Season with salt to taste. Ladle into soup bowls and
garnish with ground pepper and chives. Serves 6.