Roughly chop the nuts and mix with 150 g flour, 75 g sugar and a pinch of salt in a bowl. Melt 125 g butter and add to the mixture. Knead everything by hand to make sprinkles. Finally, pour a tablespoon of flour over it and toss it loosely under the crumble.
Slowly melt the chocolate together with 150 g butter in a water bath and let cool down a little. Meanwhile, mix the eggs, 250 g sugar, vanilla sugar and a pinch of salt. Mix 250 g flour with the baking powder and sieve over it. Finally stir in the chocolate butter and work everything into a smooth dough.
Grease a springform pan (26 cm), pour in the chocolate dough, spread the crumble on top and bake at 150-175 degrees for 35 to 40 minutes. Make a random test, later let the cake stand briefly in the tin, then remove it and let it cool down.