Melt 75 g butter in a saucepan. Add milk and remove from the heat. Mix flour, 75 g sugar, vanillin sugar, salt, yeast and cocoa powder in a bowl. Add the egg. Add the butter-milk mixture and knead with the dough hooks of the hand mixer to a smooth dough. Cover and leave to rise in a warm place for about 45 minutes.
Knead dough and roll out on a greased fat pan of the oven. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 10 minutes. Meanwhile melt 150 g butter and 175 g sugar. Fold in the cornflakes. Pour the cornflakes mixture onto the cake and bake at the same temperature for 15-20 minutes. Take the cake out of the oven, let it cool down and cut into strips
1 1/2 hours waiting time