Hairy Bikers' chestnut and chocolate roulade recipe
 This alternative Christmas log (Swiss roll packed with dark chocolate, cream and chestnut) is seriously sophisticated, but still a real crowd-pleaser. softened butter, for greasing6 large free-range eggs, separated 150g/5½oz caster sugar50g/1¾oz cocoa powder 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 squares300ml/10fl oz double cream200g/7oz chestnut purée40g/1½oz caster sugar 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 squares50g/1¾oz white chocolate, broken into squares1 tsp icing sugar 50g/1¾oz plain dark chocolate, broken into squares 50g/1¾oz white chocolate, broken into squares 1 tsp icing sugar Method 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. Chill in the fridge until ready to serve, and remove from the fridge 30 minutes before serving. Dust with a little sifted icing sugar.