Meanwhile, place chocolate in medium bowl. In 2-quart saucepan, heat whipping cream just to boiling. Pour hot cream over chocolate; let stand until mixture is melted and smooth when stirred. Using whisk, beat in espresso powder and sugar. Refrigerate chocolate mixture 1 hour, stirring occasionally, until cold. Beat cold chocolate mixture with electric mixer on high speed until soft peaks form, about 2 to 3 minutes.