Break chocolate into pieces. Chop the pistachios very finely, except for 1 tablespoon. Mix pudding powder, sugar and 4-5 tablespoons of milk. Boil up the rest of the milk and the chopped pistachios. Stir in pudding powder, bring to the boil and simmer for about 2 minutes.
Add the chocolate and melt it while stirring. Let the pudding cool down. Stir from time to time.
Whip the cream until stiff. Let vanilla sugar trickle in. Stir pudding again until smooth and fold in approx. 2⁄3 cream. Spread the cream into dessert glasses. Spray the rest of the cream as tuffs onto the cream or spread it with a spoon.
Chop the rest of the pistachios and sprinkle over the top. Keep cool until serving.