Preheat your oven to 175 degrees Celsius. Grease and flour a cake tin with a diameter of about 22cm. Whisk together the eggs and sugar using an electric whisk until pale and increased in volume.

Whisk in the vanilla sugar and baking powder. Add in the flour and continue whisking before melting the butter in a pan with the water. When the butter has completely melted, pour into the batter and continue whisking until everything is well mixed.

Pour the batter into the prepared tin and then place into the preheated oven. Bake for about 25-30 minutes, testing by sticking the cake with a fork or small skewer after about 25 minutes. Remove the cake when the skewer comes out clean.

Allow to cool for a few minutes in the tin before carefully turning out and allowing to completely cool on a wire rack while you make the whipped ganache.

Pour the cream for the filling into a small saucepan, and break the chocolate into small pieces and add to the cream. Place over a gentle heat and stir regularly until the chocolate has completely melted and combined with the cream.

Place the ganache into the refrigerator for an hour and once it is completely cool, whip it until thick like whipped cream.

Slice the now cool cake carefully into three layers using a long knife. Sandwich each layer together with half of the ganache, dropping some blueberries into the filling on each layer as you go.

Finally, whip the cream for the topping until stiff and spread liberally onto the top and sides. Decorate the cake with the raspberries and blueberries and enjoy!