Boil pudding from pudding powder, sugar and milk and let it cool. Stir every now and then to prevent skin from forming.
Drain the sour cherries well in a colander.
Mix the quark with the sugar and orange juice.
Put half of the sour cherries in a large, wide glass bowl. First put half of the pudding on top and smooth it out, then half of the quark. Then layer the remaining cherries, the remaining pudding and quark.
Carefully pour eggnog on top of the quark layer and sprinkle with grated chocolate. Then chill.