Boil 300 g cream with 1 teaspoon sugar in a pot. Finely chop the chocolate, pour the cream over it and mix until smooth. Cover the surface with foil, let it cool down for about 1 hour. Then put in a cool place for about 2 hours.
Separate eggs. Coarsely chop the pistachios, set aside 1 tablespoon. Beat the egg whites and 1 pinch of salt with the whisk of the hand mixer until stiff, finally add 75 g sugar. Whisk the egg yolks, fold in 2 portions. Sift the cocoa in 2 portions over the egg yolks and fold in the pistachios.
Line a baking tray (32 x 40 cm) halfway with baking paper. Fold a rail out of aluminium foil and push it slightly under the baking paper and fold it upwards as a border. Spread the sponge cake on the baking parchment evenly. Bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 10 minutes, remove from oven, let cool on a cake rack for approx. 10 minutes
Sprinkle the sponge cake with 1 teaspoon sugar, remove from the baking tray, pull down. Turn the sponge onto a piece of baking paper (approx. 20 x 32 cm), remove the baking paper from the sponge. Place the sponge on a cutting board or cake plate. Stir pudding powder, 2 tsp. sugar and 3 tbsp. milk until smooth. Bring 220 ml milk to the boil. Stir in the pudding powder, bring to the boil and simmer for about 1 minute. Remove from the stove
Spread the pudding evenly on the sponge cake, cover with foil, and chill for about 1 hour. Soak gelatine in cold water. Whip the chocolate cream with the whisk of the hand mixer until semi-stiff. Squeeze the gelatine, dissolve, mix with 2-3 tbsp. chocolate cream, stir into the remaining cream
Place the sponge cake in a cake frame, spread the chocolate cream on top and refrigerate for about 2 hours. Finely chop the dark chocolate coating. Bring 2 tbsp. milk and 4 tbsp. cream to the boil in a saucepan. Pour 2 tablespoons of the cream milk over the chocolate coating and stir until smooth. Alternately stir in the remaining milk and the nougat
Loosen the cake frame, spread a thin layer of icing on the cake, chill for another 30 minutes. Coarsely chop the white couverture, melt over a warm water bath, let it cool down for about 10 minutes
Spread the couverture thinly on the back of a baking tray, place in a cool place for about 15 minutes until the couverture is just firm. Use a metal spatula to peel off the rolls, place in a cool place. Cut the cake into 40 pieces (approx. 4 x 4 cm), decorate with chocolate rolls and pistachios
Waiting time approx. 5 hours