For the base
Put the flour in a heap on a work surface, mix with the cocoa, salt and sugar and make a well in the middle.
Scatter the cold butter around the well.
Break the egg into the middle, add the water and chop all the ingredients with a knife until they resemble breadcrumbs.
Quickly combine to a dough with your hands, form into a ball, wrap in cling film and chill for about 30 minutes.
Heat the oven to 180°C (160° fan).
Grease 8 ramekins.
Roll out the pastry on a floured surface and cut out 8 circles to fit the moulds, using either the rim of one of the moulds or a 10 cm cutter.
Line the bases of the greased moulds with the pastry circles.
For the filling
Mix the quark with the sugar, cornflour, eggs and lemon zest.
Whisk the cream until thick and fold in.
Fill the moulds with the mixture and smooth the top.
Bake for about 40 minutes. (Test to see if they are done by inserting a wooden cocktail stick. )
When done, leave in the oven for a further 10 minutes, with the oven switched off and the door open a crack.
Then remove and leave to cool.
Place the cheesecakes on serving plates.
Put 1/3 of each fruit into a small pan with the sugar and water and bring to a boil. Purée and push through a sieve.
Drizzle the cheesecakes with fruit sauce and top with fresh fruit.