Preheat the oven to 360º F/ 180º C. Grease two 7 inch/ 18 cm cake pans and line them with circles of parchment paper.

In a medium bowl mix together flour and baking powder.

In a large mixing bowl whip the egg whites together with the sugar until soft peaks form.

In a separate large bowl combine egg yolks, Nutella and vanilla extract. Beat with the mixer for 1-2 minutes, until creamy.

Gradually add the flour, alternating with the egg whites. Mix gently with a rubber spatula until smooth.

Divide the batter between the two pans. Bake for about 40 minutes or until a toothpick inserted in the centre comes out clean.

Let the layers cool completely before assembling the cake.

Whip the mascarpone to make it creamy. If it is too thick, add 1-2 tablespoon sour cream.

Divide the mascarpone between two bowls. Add the Nutella to the first one and whip until creamy and uniform.

Melt the kinder chocolates on a double boiler. Cool it down a bit and add it to the mascarpone. Mix with a rubber spatula until creamy.

Using a serrated knife cut horizontally the cake bases into two layers each.

Place one layer on a serving plate. Use a tablespoon to soak it with ¼ cup milk. Spread half of the kinder chocolate frosting (the lighter one) on top.

Place the second layer and soak it with another ¼ cup milk. Spread about ⅓ of the Nutella frosting. Cover with the third layer, soak it with milk and spread the rest of the kinder frosting.

Soak the top layer before covering the cake all around with the Nutella frosting. Decorate with kinder bars.

You can also reserve some frosting and add more Nutella to it and then pipe on top of the cake.