First, make the cake. Beat the eggs with the sugar, gradually add the water as well, beat until the sugar dissolves completely. Next, add the oil and vanilla and beat again.
Mix the baking soda with the flour. Add the flour mixture to the egg mixture spoon by spoon, stirring until homogeneous. Set aside 1 cup of the mixture, add the cocoa to it. Butter and flour a cake form.
Pour in part of the light mixture, then the brown mixture along the edges of the form, then repeat this process around the hole in the form. Bake at 356°F (180 °C) until ready. Leave it to cool.
Cut the cake slightly above the middle, so you end up with a sort of cap. With a spoon, dig out a channel in the cake. Fill the channel with the cream mixed with the kiwi and banana. Smear the remaining filling on top. Put the cap of the cake back on. Sprinkle with powdered sugar. Bon appetit!