Preheat oven to 180˚C. Line a 20cm round cake pan with greaseproof paper.
Place Dr. Oetker Nona Butter Cake Chocolate and eggs in a mixing bowl. Mix at medium speed for 3 minutes.
Add in butter and mix at low speed for 1 minute or until batter is smooth.
Pour the batter into the pan and bake at 180°C for 55 - 60 minutes.
Whisk whipping cream with Dr. Oetker Nona Cocoa Powder at high speed for 1 minute or until medium peaks form.
Split the cake in 3 portions lengthwise. Spread the cream evenly on the cake slices, top with sliced bananas and dust the top of cake with icing sugar.