1 (6 oz.) pkg. (1 c.) semi-sweet chocolate pieces
1/4 c. butter
1/2 c. dairy sour cream
1 tsp. vanilla
2 1/2 to 2 3/4 c. sifted confectioners' sugar

Melt chocolate pieces and butter over hot, not boiling, water; remove from hot water and blend in sour cream, vanilla and 1/4 teaspoon salt. Gradually add enough confectioners' sugar for spreading consistency; beat well. Frost tops and sides of two 9-inch layers or 10-inch tube cake.