Prepare the fondant:melt the chocolate in a bain-marie. Add the butter, leave for another minute, smooth the mixture.
Split the vanilla pod in half lengthwise. Put it in a saucepan with the cocoa and the milk. Bring to a boil while stirring. Whisk the egg yolks with the sugar in a second saucepan. Pour in the milk, whisking constantly. Cook this custard over low heat, stirring constantly until it coats the spatula. Remove from heat and let cool. Remove the vanilla pod.
Add the chocolate-butter mixture to the lukewarm cream, beating with a hand whisk. Leave the cream to cool then pour it into a 1 liter spring form mould. Smooth the surface with a spatula and refrigerate for 24 hours.
Prepare the anise sauce:pour the milk into a saucepan. Add the star anise (lightly crushed) and bring to the boil. Whisk the egg yolks with the sugar in a second saucepan. Pour in the boiling milk, whisking constantly. Cook this sauce over low heat, stirring constantly, until it coats the spatula, without ever reaching a boil. Remove from heat and let cool, whisking occasionally. Filter and reserve in the refrigerator.
When ready to serve, unmold the fondant onto a dish, first immersing the bottom of the mold for a few seconds in hot water. Pour the anise sauce all around the cake or serve it in a sauceboat.
