1 1/2 c. butter, softened
2 c. confectioners sugar
3 lg. egg yolks
1 c. semi-sweet chocolate pieces, melted

In a large bowl mix with mixer at high speed sugar and butter until light and fluffy. Beat in egg yolks one at a time. Gradually beat in chocolate until blended and spreadable. If too soft, refrigerate until cold; beat until fluffy.