Saute mushrooms in butter 2 minutes. Stir in flour. Dissolve cubes in boiling water. Blend into flour mixture. Cook mixture until it boils and thickens. Lightly beat egg yolks with half
Cook until hot, not "boiling". Stir in chicken and nutmeg. Make crepes. Fill crepes. Top with extra sauce. Cover and bake at 375 degrees about 30 minutes.