Grease a springform pan (26 cm Ø) and dust with flour. Coarsely chop the chocolate coating and melt it in a hot water bath, let it cool down a little. Cream butter, 100 g sugar, vanilla sugar and 1 pinch of salt with the whisk of the hand mixer.
Stir in the eggs one by one. Mix flour and baking powder, sieve over it and stir in. Stir in liquid chocolate coating.
Preheat oven (electric cooker: 175 °C/circulating air: 150 °C/gas: level 2). Spread the dough into the tin and bake in the hot oven for 20-25 minutes. Take out, let cool in the form for about 15 minutes. Remove from the mould and let cool completely.
For the cream, peel the oranges so that the white skin is completely removed. For 2 oranges, cut out the fillets between the parting skins and cut them into pieces. Squeeze the parting skins and collect the juice.
Soak gelatine in cold water. Whip the curd, tiramisu cream, orange juice and 100 g sugar with the whisks of the hand mixer for 3 minutes. Squeeze the gelatine, dissolve over low heat and mix with 2 tbsp. cream.
Then stir into the rest of the cream. Fold in orange pieces. Close the edge of the mould around the base and spread the orange cream on top. Chill the cake for at least 3 hours.
Peel the rest of the orange with white skin and cut into slices. Remove the cake from the tin. Dust with cocoa and decorate with the oranges.