Take the chocolate mousse quenelle out of the package. Put on a plate and cover with plastic. Defrost in the fridge.
Grind the cookies in to a fine crumble. Melt the butter and mix with the ground
cookies. Spread between plastic sheets. Make a thin cookie base with a rolling pin. Place in the fridge. Use a round cookie cutter to cut circles out of the cookie base.
Let the sugar caramelize in a cooking pot on low heat. Meanwhile bring the cream to a boil. When the sugar reaches the desired caramel colour, slowly pour in the warm cream. Stir well and add the butter and the salt. Stir until both have dissolved. Finally, add the dark rum. Let cool down and transfer to a piping bag. Keep refrigerated.
Spread the chocolate callets on a baking tray with silicone baking sheet. Bake for 20 minutes in a 125 °C oven. Separate the callets with 2 forks and stir them. Place back in the oven for 20 minutes on 150 °C. Let cool down. Store in a dry, airtight container.