Preheat the oven to 180 ° C top / bottom heat, defrost frozen berry mixture and collect the juice.
Mix all the ingredients for the dough and process into crumble. Grease a springform pan (26 cm) and process the crumble in the form to a smooth base. Refrigerate.
For the quark topping, put all the ingredients in a bowl and stir to a smooth mass. Spread on the dough base and bake for about 60 minutes in the preheated oven on the lower rail.
After 60 minutes, let the cake rest for 15 minutes with the oven door open. Let cool completely on a kitchen rack. It is best to put it in the refrigerator overnight.
Spread the drained berry mixture on the cake. Prepare the icing according to the instructions on the package, using the juice that has been collected. Spread quickly on the fruit, leaving 1 cm free. Let cool for 30 minutes, then loosen the springform pan.
Chill the finished cake.
ATTENTION! Please rather take 20% quark and express something. The cake is too moist with 40% !!