1. Preheat the oven to 180C/Fan 160C/350F/Gas 4. Grease and baking parchment line a 33x23 (13x9in) Swiss roll tin.

2. Place a large bowl over a pan of hot water, add the eggs and sugar, then use an electric whisk to beat until the mixture is thick enough to leave a ribbon trail when the beaters are lifted.

3. Sift the flour and cocoa over the egg mixture and gently fold in. Pour into the prepared tin and bake for 15mins or until the mixture bounces back when lightly touched in the centre.

4. Tip the cake out onto a sheet of baking parchment, peel away the lining paper, then roll up the sponge along the long edge in the fresh piece of paper and leave to cool on a wire rack.

5. Prepare the icing: place the cream and chocolate in a small pan and gently heat, without boiling, stirring until the chocolate has melted. Remove from the heat and stir until smooth. Leave until cold then chill for 10 mins.

5. For the filling, beat the caster sugar into the chestnut puree. Whip the cream until it forms soft peaks, then fold in the chestnut puree.

6. Unroll the sponge, then spread the chestnut cream over the top. Roll the cake back up to form a log shape. Place seam side down on a serving plate.

7. Lightly whip the chilled icing until it is thick, then spread it over the top and sides of the cake. Scatter the broken flakes over the icing, then lightly dust with icing sugar. Serve chilled.