For the dough, grease the fat pan of the oven (deep baking tray; approx. 32 x 39 cm) and dust with flour. Preheat the oven (electric cooker: 180 °C/circulating air: 160 °C/gas: see manufacturer). Coarsely chop the chocolate coating.
Bring the cream to the boil in a saucepan while stirring. Melt butter first, then chocolate coating while stirring at medium heat. Mix flour, baking powder and 1 pinch of salt. Mix eggs, brown sugar, sugar and vanilla sugar with the whisk of the mixer.
Whip for about 5 minutes until thick and creamy. Alternately stir in liquid chocolate butter, flour mixture and milk. Fill the dough into the fat pan and smooth it down. Bake in a hot oven for approx. 20 minutes.
Let the cake cool down for about 3 hours.
For the glaze, chop the couverture and coconut oil into coarse pieces, place in a small bowl and carefully melt over a warm water bath while stirring. Cake.