For the banana cake, first prepare the cake base. To do this, beat the butter, sugar and eggs until fluffy, mix the flour, cocoa and baking powder and stir into the fluffy mixture.
Now fill the dough into a springform pan ( 26 cm ) and bake at 175° for about 35 minutes. For the cream, stir the cornstarch with a little milk until smooth, bring the remaining milk, sugar and vanilla pulp to a boil and stir in the cornstarch.
Soak the gelatine in cold water, squeeze it out and stir it into the warm mixture. Allow the cream to cool slightly. In the meantime, cut the cake base in two.
Spread the first cake layer with jam, put the second one on top and spread a little cream on it. Now place the bananas on top and spread the remaining cream on top. Cover with the last cake layer and cover the banana cake with whipped cream.