Preheat the oven to 160C. Grease and line a 20cm loose bottomed cake tin. In a food processor blitz the digestive biscuits until they resemble fin breadcrumbs. Alternatively bash them in a food bag using a wooden rolling pin.
Melt the butter in a saucepan, but make sure you don’t burn it. Add the biscuits and mix again until they are fully coated.
Press the base into the prepared tin and once even set aside to set in the fridge.
For the filling mix the quark with the cream, sugar and eggs then whisk to combine. Melt the chocolate either in a bain marie or microwave and stir into the cream mixture, before sieving in the cornflour and cocoa. Add the vanilla. Whisk again until smooth.
Pour the mixture on top of the base then bake in the preheated oven for roughly 1 hour or until just set – the middle will still have a little wobble.
Turn off the oven and open the door, keeping the cheesecake in the oven. Leave for 20 minutes then remove and allow to cool completely.
Once cool whip the cream with the icing sugar until soft peaks forms, then spread over the top of the cheesecake.
Finish with shaving of the excess dark chocolate. Keep in the fridge until ready to serve.