Coarsely chop 200 g dark chocolate and milk chocolate. Heat 350 g cream in a saucepan and remove from the heat. Dissolve the chocolate in it while stirring until an even, smooth chocolate mass is formed. Put the mixture into a mixing bowl, let it cool down and put it in a cool place for about 2 hours
Bring milk, fat, vanillin sugar and salt to the boil in a small pot. Mix the flour and cocoa, add to the pot at once and stir with a stirring spoon until the mixture conglomerates into a lump and a skin forms at the bottom of the pot. Pour the dough into a mixing bowl and stir in the eggs one by one with the dough hooks of the hand mixer. Let dough rest for about 20 minutes
Place the grid on the bottom of the oven and place a flat, ovenproof dish with hot water on top. Put the choux pastry in a piping bag with a large perforated spout (14 mm Ø). Spray approx. 25 tuffs just under the size of a walnut onto a baking tray lined with baking paper. Bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 20 minutes. Cut open the cream puffs and let them cool down
Whip the chocolate cream with the whisk of the hand mixer until creamy. Pour into a piping bag with a large star-shaped spout and fill the sliced cream puffs with the chocolate cream. Chill for about 20 minutes
Coarsely chop 50 g dark chocolate and melt it together with 50 g cream and coconut fat in a small pot at low heat while stirring. Let it cool down a little bit. Coarsely chop the white chocolate coating and melt it over a warm water bath and put it in a disposable piping bag. Cut off a small corner. Put a small blob of dark chocolate icing on each cream puff and decorate with some white couverture. Chill again briefly
waiting time approx. 1 3/4 hours