1. In a bowl, break the 5 eggs and separate the whites from the yolks.2. Prepare the mousse. Boil 100 ml of water with 80 g of sugar for 5 minutes. Beat the 5 egg yolks with 40 g of sugar until whitened. Add the boiling syrup while whisking and beat until cooled.3. Melt the grated chocolate in a double boiler. Mix the softened butter with the cooled chocolate; incorporate the egg yolks and the 5 whites beaten into stiff peaks with a pinch of salt.4. Divide the mousse into serving glasses and smooth with a spatula. Refrigerate for 5 hours.5. Prepare the pistachio cream. Boil the milk with the split vanilla pod. Let it infuse off the heat for 20 minutes. Reduce the pistachios to a fine paste with the powdered sugar and 2 tablespoons of warm water.6. Beat the egg yolks and 60 g of powdered sugar until whitened. Incorporate the warmed milk without the pod. Thicken the cream over low heat, stirring until it coats the spoon. Add the pistachio paste off the heat; let it cool. Add the kirsch and refrigerate.7. Before serving, pour the pistachio cream over the chocolate mousse. Decorate with dark chocolate shavings.