Melt the butter in a small pot. Put cookies and shortbread in a freezer bag and crumble finely with a kitchen roll. Wrap a kitchen board smoothly with aluminium foil, spread a thin layer of oil on the foil. Place 4 dessert rings (approx. 8 cm Ø) on top. Mix cookie crumbs and butter. Spread evenly into the dessert rings, press them together with your hands to form a base (it sticks a little). Chill for about 30 minutes.
Pour the cherries into a sieve, drain well and collect the juice. Fill up the cherry juice with water to make 500 ml of liquid. Stir sauce powder, 5 tbsp. liquid and 2 tbsp. sugar until smooth. Bring the remaining liquid to the boil, stir in the sauce powder, bring to the boil and simmer for approx. 1 minute, stirring several times. Fold in cherries, except for 1 heaped tbsp. for the cream. Pour into a bowl and let cool, stirring several times
For the cream, dab the cherries dry with kitchen paper and mash them with a fork. Whip the cream until stiff. Mix quark, mascarpone, vanillin sugar and 3 tbsp. sugar. Fold in the cherries. Fold in cream. Pour cream into the dessert rings, chill for about 1 hour
Remove the tartlets from the dessert ring with a knife, carefully peel off the foil. Arrange the tartlets with some cherry sauce on plates. Add the rest of the cherry sauce
waiting time approx. 1 1/4 hours