Chocolate Sour Cream Frosting
["1 (12 oz.) pkg. (2 c.) semi-sweet chocolate pieces", "1/2 c. butter", "1 (8 oz.) carton sour cream", "4 1/2 c. powdered sugar, sifted"]
["In large saucepan, melt chocolate and butter over low heat, stirring frequently. Cool for 5 minutes. Stir in sour cream. Gradually add powdered sugar, beating until smooth. Frosts tops and sides of three 8-inch cake layers."]
["semi-sweet chocolate pieces", "butter", "sour cream", "powdered sugar"]