Crackle Top Fudge Sauce

In a saucepan over medium heat combine the confectioners' sugar butter and heavy cream. Cook stirring constantly until smooth. Do not allow the mixture to boil. Remove from heat and stir in chocolate chips and unsweetened chocolate until melted and smooth. Allow the mixture to cool slightly before using. May be kept in a covered container for a few days at room temperature or refrigerated for up to 1 week.