Whisk the eggs and sugar in a large bowl to a ribbon stage; fold in the flour, butter and camp coffee then pour into a greased, lined 22cm cake tin and bake for 30 to 35 minutes. Remove from the oven then cool in the tin for 10 minutes before placing on a cooling rack.
To make the icing, whisk together the icing sugar, camp coffee essence and water.
Next fold the chestnut puree through the cream.
Using a knife, split the cake in 2 horizontally then spoon over the chestnut cream. Place the top half of the cake on the cream and drizzle over the icing. Decorate with marron glace.