Coarsely chop 150 g dark chocolate. Carefully melt fat and chocolate over a warm water bath. Leave to cool slightly. Finely chop the chocolate bars. Whisk eggs, sugar, vanilla sugar and salt with the whisk of the hand mixer for about 5 minutes until thick and creamy
Put the melted fat-chocolate mixture into a mixing bowl. Stir in egg-sugar cream. Mix flour and baking powder, sieve over it and stir in briefly. Fold in chocolate bar. Pour the dough into a well greased, flour-sprinkled box cake tin (25 cm long; 1 1/2 litre capacity) and smooth it down. Bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 1 hour. After 45 minutes cover with aluminium foil if necessary
Let the cake rest in the mould for about 5 minutes, then turn out of the mould and let it cool down on a cake rack
For the icing, roughly chop 200 g dark chocolate. Put cream and coconut oil in a small pot and heat it up. Remove from heat and let the chocolate melt in it. Let the icing cool down until it has become a little thicker. Coat the cake with it, wavy the surface. Let it dry. Whipped cream tastes good with it
waiting time approx. 4 hours