Cream 1: Heat the liquid cream, taking great care not to boil it, add the chopped chocolate and mix vigorously until it melts, then remove from the heat.
We proceed identically for cream 2.
Let the 2 compositions cool overnight, when they are cold, mix them until they harden, and in the one with dark chocolate, add the rum essence. Hydrate the gelatin according to the instructions on the envelope, then melt it on a steam bath and add it to the creams.
Crush the biscuits and mix them well with the melted butter, wallpaper the bottom of a form with the detachable edges with this mixture. We start to put 2 lg of black cream in the center of the tray, then 2 lg of white cream and again the black one until they run out, cover the tray and let it cool for at least 6 hours