Grease the fat pan of the oven (deep tray; approx. 32 x 39 cm) and dust with flour. Preheat the oven (electric cooker: 180 °C/circulating air: 160 °C/gas: see manufacturer). Pour cherries into a sieve and drain well.
Mix flour and baking powder in a bowl. Cream eggs, sugar, vanilla sugar and 1 pinch of salt with the whisk of the mixer for about 5 minutes. Add butter in small pieces to the egg mixture and whisk smooth with the whisks of the mixer.
Stir in flour mixture and 1 tablespoon of milk.
Fill half of the dough into the fat pan and smooth it down with a dough scraper. Stir the baking cocoa and 3 tbsp. milk into the remaining dough. Spread the chocolate dough evenly over the light-coloured dough, also smooth it down.
Spread cherries on top. Bake in a hot oven for approx. 25 minutes (stick test). Let the cake cool down for at least 4 hours.
For the cream, stir butter and icing sugar briefly with a tablespoon until smooth. Spread evenly on the cooled cake with a dough scraper.
For the glaze, chop the couverture and coconut oil into large pieces. Melt together with the cream in a pot at low heat while stirring. Let the glaze cool down for 10-15 minutes. Then spread on the cake, smooth it down and put it in the fridge for about 1 hour.