Cut the chocotone into cubes and distribute them on the bottom of a 28cm roasting pan with a removable bottom, lined with acetate.
Melt the semisweet chocolate and in parallel beat the fresh cream until it reaches the whipped cream point, then incorporate it into the chocolate in three steps (put a little and mix, then a little more and mix and lastly the last part) allows the air to fully enter the chocolate leaving the mousse well aerated
Pour the mousse over the chocotone and put it in the fridge for 4 hours.
Mix the milk chocolate with the 80g of cream, mix until you get a smooth and shiny ganache.
Unmold the pie, cover with the ganache and finish with the chestnuts.