Place the butter in a bowl, whisk in the sugar and salt using the whisk attachment on a hand mixer. Whisk in the egg. Add the flour, mix quickly to form a soft dough; do not knead. Flatten the dough, cover and chill for approx. 30 mins.
Chill one quarter of the dough for the crumble topping. Roll out half of the remaining dough on to the prepared cake tin base, close the tin frame. Shape the remainder of the dough into a roll approx. 60 cm long, place around the edge of the pastry base, press gently and pull upwards approx. 2 cm. Prick the base firmly with a fork, refrigerate for approx. 15 mins.
Spread half of the gooseberries over the pastry base. Mix the quark with all the other ingredients up to and including the salt, spread on top of the gooseberries. Top with the remaining gooseberries. Using your hands, crumble the chilled pastry and scatter over the top.
Approx. 75 mins. in the lower half of an oven preheated to 180°C. Remove from the oven, allow to cool slightly, remove the tin frame, slide the cake onto a cooling rack and leave to cool completely.