In medium-size bowl, on low speed, beat remaining 3 tablespoons liqueur and mascarpone just until blended. Gradually beat in 7 tablespoons water until smooth. Sprinkle mousse mix over top. Beat on low speed 1 minute; increase speed to medium-high and beat until thick and lightened in color, 2 to 3 minutes. Transfer mixture to large pastry bag or plastic food-storage bag fitted with large star tip. Pipe mousse into cookie-lined cups. (Or, spoon 2 slightly rounded tablespoons into each cup.) Refrigerate at least 1 hour to firm.