Drain the peaches and collect the juice. Puree one half, cut the other half into wedges. Add the mascarpone and quark to the peach puree and stir. Then add vanilla sugar.
Soak the ladyfingers in peach juice and, if alcoholic, peach liqueur and place on the bottom of a baking dish or bowl. Spread the cream on top and cover with the columns. Chill for at least 1 hour.