Grease the springform pan (26 cm Ø). Mix flour, baking powder, 225 g sugar, vanillin sugar, salt, butter in flakes and 1 egg yolk first with the dough hooks of the hand mixer and then briefly with your hands to form crumbles
Drain gooseberries well. Press approx. 2/3 of the sprinkles in the springform pan evenly on the base. Spread the gooseberries, up to 10-16 pieces for decorating, on top, leaving an approx. 1 cm wide edge
Mix 600 g sour cream, 5 eggs, 150 g sugar and pudding powder with the whisk of the hand mixer for about 1/2 minute. Pour over the gooseberries. Bake in the preheated oven (electric cooker: 175 °C/circulating air: 150 °C/gas: level 2) for approx. 20 minutes
Knead the rest of the crumble and approx. 2/3 brittle. Spread on the sourdough and bake at the same temperature for about 40 minutes. Leave to rest for approx. 10 minutes in an open oven that is switched off. Then remove from the edge with a knife. Leave to cool in the mould for about 4 hours
Mix 100 g sour cream and 2 tablespoons of sugar. Pour in splotches on the cake. Decorate the cake with the remaining brittle and gooseberries
Tips for crumble cakes
Delicious variations: mix a little cinnamon, lemon peel, vanilla or bitter almond flavour into the crumbles as desired. Or replace about half of the flour with ground almonds, hazelnuts or walnuts. This keeps crumble cakes fresh longer: after cooling, store in aluminium foil or in a well-closing plastic tin