Combine heavy cream, Kahlua, confectioner's sugar, and espresso. Beat until lightly whipped and soft peaks form. Reserve half and refrigerate the remaining half.
With beater on low, mix Mascarpone and dessert sauce until smooth. Fold in reserved whipped cream until well blended and light in texture.
Spoon mixture into demitasse cups, leaving about 1/8-inch space from the top.
Top mixture with a dollop of remaining cream and spread out to touch the sides of the cup, creating a "faux" foam.
Sprinkle top with espresso powder and serve a small biscotti.