Melt the couverture over a warm water bath. Drain the cherries and let them drain well. Cream butter, sugar, salt and vanilla sugar with the whisk of the hand mixer. Stir in the eggs one after the other.
Stir in the chocolate coating. Mix flour and baking powder and stir in. Fold in cherries. Pour into a greased, flour-dusted box form (11 x 30 cm, approx. 1.75 litres capacity) and bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see
manufacturer) bake for about 50 minutes. Take out and let cool down.
Sieve the icing sugar into a bowl and stir it with the liqueur until smooth. Carefully remove the cake from the mould, place it on a cake rack and cover with icing. Allow the icing to set, transfer the cake to a cake plate.
Dust with cocoa powder.