Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
   2      tablespoons   butter
   2      tablespoons   flour
   2      cups          clear chicken broth
   2      tablespoons   chopped fresh mushrooms
                        (or canned sliced mushrooms)
   1      small         bay leaf
   1      pinch         thyme
     1/2  teaspoon      salt
     1/4  teaspoon      white pepper
     1/8  cup           heavy cream
   2                    egg yolks
   1      pinch         grated nutmeg

Preparation:

Heat butter in heavy saucepan. Stir in flour. Add chicken broth and cook, stirring constantly, until smooth. Add mushrooms, nutmeg, bay leaf, thyme, salt, and pepper. Cook over low flame, stirring occasionally, for 30 minutes. Add cream. Stir in yolks. Heat but do not allow to boil. Serve hot. Recipe Source: THE ART OF FRENCH COOKING by Fernande Garvin