Drain the morello cherries while collecting the juice.
Bring the juice from the morello cherries with the cake glaze to the boil according to the instructions on the packet, then add the morello cherries and fold in. Pour into a shallow bowl and let cool down.
Mix the quark with the sour cream and vanilla sugar. Whip the cream until stiff and fold in. Spread this mixture on the cooled cherries and sprinkle with dark chocolate flakes (possibly also possible with eggnog).