Bring the milk, the salt and Végétop to a gentle simmer and add the agar agar.
Whisk the egg yolks with sugar then temper with the warm cream mixture.
Return to the heat and cook to 82°C.
Pour over the dark chocolate and blend until smooth.
Pour in a container and let cool overnight.
Next day, blend until smooth.
Transfer to a piping bag with a smooth nozzle.