For the Nutella cake, separate the eggs. Cream yolks with sugar, gradually add oil and water. Mix flour with baking powder and gently stir in.
Beat egg whites until stiff and also fold in carefully. Spread the dough on a baking tray and bake at 170 °C for approx. 25-30 minutes. In the meantime, prepare the cream.
Cream the butter and then stir in the Nutella by the spoonful. Spread this cream on the cooled cake.
Finally, whip the cream until stiff and spread on the cream, sprinkle with chocolate flakes.