Drain the cherries well. Cream 250 g butter and 250 g sugar. Stir in eggs one after the other. Mix flour, baking powder and cocoa and stir in briefly. Spread the dough evenly with a dough card on a greased baking tray (38 x 32 cm).
Spread the cherries on the dough. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 35 minutes. Let them cool down. In the meantime, stir pudding powder, 6 tablespoons of sugar and 10 tablespoons of milk until smooth.
Bring the remaining milk to the boil, stir in the pudding powder and bring to the boil again briefly. Place in a bowl, cover with foil and allow to cool. Whip 250 g butter until creamy white. Stir the pudding briefly and add to the butter by the spoonful, stirring continuously.
Spread butter cream on the cake and chill until the cream is firm. Melt the chocolate coating and fat in a hot water bath. While stirring, allow to cool slightly and spread on the cake. Use a cake comb to draw wavy strips through the chocolate.
Let the chocolate set. Cut the cake into about 24 pieces.