Wash the currants, drain them and remove the panicles. Separate eggs, beat egg whites into snow. Beat the egg yolks with sugar and warm water until frothy. Mix with baking powder, cocoa, rum and hazelnuts. Mix well and finally fold in the egg whites.
Pour into a greased springform pan and bake at 175 ° C for 35 - 45 minutes. Cool well and remove from the mold.
For the topping: mash 2 bananas and spread them on the cooled base. Whip the cream (possibly with cream stiffener, but it doesn`t have to be) and spread it over the bananas. Spread the currants over the cream and chill for at least 2 hours.
Blackberries, raspberries and gooseberries are also suitable for this cake!