Grease a fat pan (approx. 32 x 39 cm; approx. 3.5 cm deep) and dust with flour. Coarsely chop white couverture and melt with butter in a hot water bath while stirring constantly. Leave to cool for about 15 minutes.
Drain the cherries. Beat eggs, sugar, vanilla sugar and 1 pinch of salt for 7-8 minutes until fluffy. Stir in the couverture butter mixture. Mix flour and baking powder, fold in with a whisk.
Spread on the fat pan. Spread cherries on top. Bake in the preheated oven (electric cooker: 175 °C/circulating air: 150 °C/gas: level 2) for 35-40 minutes. Let them cool down.
Coarsely chop the dark chocolate coating for the icing. Melt in a small pan with cream and white fat while stirring at low heat. Allow to cool for approx. 5 minutes until the mixture thickens a little, stirring more often.
Pour on the cake, spread. Chill for about 2 hours. Decorate with chocolate rolls.