Add the egg yolks, the sugar and vanilla sugar, beat until frothy, add the softened butter (keep 10g for the baking pan) in the bowl and continue to stir until frothy. Now sift the flour, cornstarch with baking powder over it, add cocoa and the chilli flakes. Mix everything to a homogeneous mass (approx. 5 min.). Finally, fold in the ice cream mass with a curler (fork also works). Please don't stir anymore! Bake everything in a round springform pan (D = 25cm) at 175 ° C (preheated) in the oven, on the middle rack, for approx. 35 minutes. After baking, divide the cake in the upper third, cut a little all around the edge with a knife, then insert a string into the cut edge and pull the two loose ends hanging out crosswise. If you don't have a thread at hand, you can try your luck with a long knife (min. 27 cm). Turn the cake topper to cool. Hollow out the cake base with a teaspoon approx. 1 cm deep (leave an approx. 1 cm thick rim on the side) and add the crumbs to the bowl with the crumbled Rond Noir and mix with the chocolate flakes.