Separate eggs. Beat the egg whites, vanillin sugar and 100 g sugar with the whisks of the hand mixer until stiff. Stir in egg yolks. Carefully fold in starch, flour and cocoa. Line the bottom of a springform pan (26 cm Ø) with baking paper.
Fill in the sponge mixture and smooth it down. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for 12-15 minutes. Take out, turn onto a cake rack, remove baking paper, let the base cool down.
Soak gelatine in cold water. Mix mascarpone, 75 g sugar and 150 ml advocaat. Whip 400 g cream until stiff. Squeeze out the gelatine, dissolve and stir in 4 tbsp. mascarpone and egg liqueur mixture.
Stir the gelatine into the mascarpone egg liqueur mixture. Carefully fold in the cream.
Cut the sponge in half horizontally. Place the lower sponge cake on a cake plate and enclose with a cake ring (26 cm Ø). Spread the advocaat cream on top, place the upper sponge cake on top. Chill for at least 3 hours.
Peel chips from the chocolate with a peeler. Whip 400 g cream until stiff. Carefully remove the cake from the cake ring, spread with approx. 300 g cream. Pour the remaining cream into a piping bag with a small nozzle and decorate the cake with it.
Press the chocolate chips to the edge. Spread 50 ml advocaat on the cake.