Preheat the oven to 180°C, line the base of a 9-inch springform pan with parchment and lightly grease the sides.
Set a heatproof bowl over a pan of lightly simmering water, making sure the bowl doesn't touch the water. Add the chocolate and butter the bowl and allow to melt, stirring occasionally.
In a medium bowl whisk the chestnut puree, light brown sugar and egg yolks together until thickened and pale.
In a clean bowl whisk the egg whites until they hold soft peaks then slowly pour in the caster sugar and whisk until the meringue is stiff and shiny.
Whisk the chocolate into the egg yolk mixture then mix in a third of the meringue. Gently fold in the rest of the meringue trying to knock out as little air as possible.
Pour the batter into the prepared pan and level gently. Bake in the preheated oven for 35-40 minutes or until the cake is risen and has a thin cracked top. Remove from the heat and allow to cool for 10 minutes before removing the springform collar, to cool completely.
For the chestnut cream place the cream and puree in a bowl and whisk to combine. If you prefer a pouring consistency leave it there and serve but if you want it thicker continue whisking until the cream holds very soft peaks.
Recipe courtesy of Edd Kimber.