Melt 50 g chocolate and coconut oil in a bowl over a warm water bath. Spread a thin layer of chocolate on a cool marble board or the back of a baking tray and place in a cool place. Once the chocolate is firm, scrape with a spatula or pallet of rolls. Put the rolls in a cool place
Chop the remaining chocolate. Boil up the cream and melt the chocolate in it. Let the chocolate cream cool down, then chill for about 2 hours
Beat the eggs with 3 tablespoons of cold water until stiff. Add sugar and vanillin sugar. Mix flour, cocoa, starch and baking powder, sieve onto the egg foam and fold in. Grease the bottom of a springform pan (26 cm Ø). Pour in the sponge mixture and smooth it down. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for about 20 minutes. Let them cool down
Cut the sponge in half horizontally. Briefly whip the ganache with the whisk of the hand mixer. Spread 1/4 of the cream on the lower cake base. Peel and slice the bananas and spread evenly on the cream. Spread 1/4 of the cream on the bananas and smooth it down. Add the second cake base. Spread the rest of the cream on the cake, cover with chocolate rolls and dust with cocoa
waiting time approx. 2 hours