For the cherry tiramisu, wash and pit the cherries. Place in a saucepan with the sugar, vanilla sugar and cherry liqueur, heat and cook for about 5-10 minutes until the cherries lose their juice. Remove the cherries from the heat, drain the juice and set both aside.
Separate the egg whites from the yolks and mix the yolks with the mascarpone and sugar. Beat the egg whites until stiff and then gently fold into the mascarpone mixture.
Now briefly dip each biscuit in the cherry juice and line the bottom of the mold with the soaked biscuits. Spread some of the cherries on the bottom and spread with the mascarpone cream. Then put another layer of biscotti and repeat this process until the mold is full. The top layer should be a mascarpone layer.
Chill the cherry tiramisu in the refrigerator for at least 2 hours and sprinkle with chocolate flakes before serving.