Cut the vanilla pod in half lengthwise and scrape out the pulp with the back of a knife. Boil up double cream, cream, vanilla pulp and scraped out pod. Mix sugar and egg yolks with the whisk of the hand mixer until the mixture is thick and almost white. Stir 4 tablespoons of the cream mixture into the egg mixture and slowly stir in the rest of the boiling cream. Stir constantly until the cream is thick and almost white. Pour cream into 4 small glasses and chill for about 2 hours. Just before serving, use a peeler to slice the chocolate onto the cream.