Mushroom Turnovers

Recipe Instructions FOR THE DOUGH: Cream ingredients thoroughly and chill. FOR THE FILLING: Sautee onion and mushrooms in butter; add remaining ingredients, except sour cream, and cook until thickened. Stir in sour cream. Divide dough in half and roll each half thinly. Cut in rounds and place as much of the mushroom mixture on each as possible; fold over to make half-round and seal. May be frozen at this point. Preheat oven to 450F. Remove desired quantity from freezer; pierce each top with knife point and brush each with a mixture of one egg yolk, beaten with 1 teaspoon water. Bake 12 to 15 minutes until golden. Makes at least 4 dozen. You may have some mushroom mixture left over.