Preheat the oven to 180 °C (air circulation).
Preheat the oven to 180 °C (air circulation).
For the chocolate sponge: whisk the eggs with the sugar, vanilla sugar and salt until fluffy. Sieve the flour with the cocoa powder and carefully fold into the egg mixture. Spread onto a baking tray lined with baking paper and bake in the preheated oven for approx. 25 minutes.
For the filling: whisk the unchilled QimiQ Classic smooth. Cut 2/3 of the sponge base into small cubes and place into a mixing bowl. Add the remaining ingredients and mix until the mixture becomes moist.
Place the remaining sponge base into an oblong tin. Spread the filling on top and cut into cubes (3x3 cm).
Decorate with the icing as required.