Place chocolate and orange liqueur in top of a double boiler. Bring water to a boil in bottom of double boiler; remove from heat. Place chocolate over simmering water, and cook, stirring occasionally, until chocolate melts. Let cool to lukewarm.
Beat whipping cream at medium speed with an electric mixer until foamy; gradually add powdered sugar, beating until soft peaks form.
Fold about one-fourth of whipped cream into melted chocolate, working quickly; fold chocolate mixture into remaining whipped cream.
Spoon evenly into individual small serving cups. Chill until ready to serve. Dollop with Orange Whipped Cream.