Ingredients

• softened butter
• for greasing
• 6 large free-range eggs
• separated
• 150g/5½oz caster sugar
• 50g/1¾oz cocoa powder
• 150g/5½oz plain dark chocolate
• broken into squares
• 300ml/10fl oz double cream
• 200g/7oz chestnut purée
• 40g/1½oz caster sugar
• 50g/1¾oz plain dark chocolate
• broken into squares
• 50g/1¾oz white chocolate
• broken into squares
• 1 tsp icing sugar

Directions

• Preheat the oven to 180C/160C Fan/Gas 4. Line a 23 x 33cm/9x13in Swiss roll tin with baking parchment
• grease with a little butter and set aside. Put the egg yolks and sugar in a large bowl and whisk with an electric whisk until thick and creamy.
• Sift the cocoa powder over the egg mixture and whisk in thoroughly. Wash and dry the beaters.
• Whisk the egg whites in a clean bowl until stiff but not dry. Fold a third of the egg whites into the cocoa mixture
• then gently fold in the rest until evenly distributed. Pour into the prepared tin and spread gently with a spatula.
• Bake in the centre of the oven for 20-25 minutes
• or until risen and just beginning to shrink away from the sides of the tin. Remove from the oven
• loosen the edges with a round-bladed knife and leave to stand for a few minutes – the cake will sink down into the tin. Place a piece of baking parchment on the work surface
• turn the cake onto the parchment and leave to cool completely.
• To make the filling
• melt the chocolate with 150ml/5fl oz of the cream in a non-stick pan over a low heat
• stirring occasionally until smooth. Remove from the heat.
• Put the chestnut purée in a food processor with the sugar. With the motor running
• slowly add the melted chocolate and cream and blend until smooth and light. Trim the edges off the cooled chocolate sponge and gently spread with the chestnut mixture.
• Whip the rest of the cream until soft peaks form when the whisk is removed from the bowl
• and spread it over the chestnut and chocolate filling. Using the parchment paper to help you
• roll the cake up from one of the short sides and carefully lift it onto a wire rack.
• To make the topping
• melt the dark and white chocolate in two heatproof bowls set over pans of simmering water until smooth
• stirring occasionally. Using a teaspoon
• drizzle the melted chocolate over the roulade and leave to set for at least 30 minutes.
• Chill in the fridge until ready to serve
• and remove from the fridge 30 minutes before serving. Dust with a little sifted icing sugar.