Mix the pudding powder according to the package instructions (here with the cherry juice). Bring the cherries to the boil with the remaining juice and stir in the mixed pudding powder. Put the thickened cherries in a bowl or baking dish and let cool.
Beat the cream quark and sugar with the hand mixer. Stir in the sour cream with a whisk.
Whip the cream with the vanilla sugar and fold into the quark mixture. Spread over the cherries. Let cool in the refrigerator, about 2 hours.
Cover all of this with eggnog and cover with grated chocolate.