1In a small bowl, combine the water, coffee granules, liqueur, and vanilla; stir to dissolve the coffee then set aside. In a large bowl, beat the mascarpone cheese, egg substitute, and sugar until smooth; set aside.
In a medium bowl, beat the heavy cream until stiff peaks form. Fold half of the whipped cream into the cheese mixture until thoroughly combined.
Line the bottom of an 8-inch square baking dish with one package of ladyfingers, slightly overlapping to fit. Spoon half of the coffee mixture over the ladyfingers. Spoon half of the cheese mixture evenly over the ladyfingers.
2Layer with the remaining package of ladyfingers and repeat with the coffee mixture and cheese mixture. Spoon the whipped topping over the top and sprinkle with the cocoa. Cover and chill for at least 3 hours before serving.
Mascarpone cheese is a fresh Italian double cream cheese that is buttery smooth in texture and can often be found in supermarket deli departments. If it's not available, you can substitute cream cheese beaten with a little milk until creamy and smooth.