Wash and clean the gooseberries and let them drain well in a sieve. Put flour, oat flakes, butter in pieces, sugar, salt, vanillin sugar in a large mixing bowl. Mix with the dough hooks of the hand mixer. Then work into crumbles with your hands and fold in the gooseberries
Spread the crumble mixture on a greased baking tray (32 x 39 cm) and bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 30 minutes. Remove and let cool on a cake rack. Cut the cake into square pieces (approx. 6 x 6 cm)