• Making time 25 minutes
• Preparation time  20 minutes

Ingredients

• 125 g plain dark chocolate
• Five eggs, separated
• 175 g caster sugar, plus an extra sprinkling
• Two tablespoons cocoa powder sifted
• Icing sugar, for dusting

For the filling:

• 250 g unsweetened chestnut puree
• Four tablespoons of icing sugar
• Two tablespoons brandy
• 250 ml double cream

Love can change a person the way a parent can change a baby-awkwardly, and often with a great deal of mess.

– Lemony Snicket

Preparation:

1. Melt the chocolate in a heatproof bowl set over a saucepan of simmering water, stirring occasionally, remove from the heat and leave to cool for 5 minutes
2. Put the egg yolk in a bowl add the sugar and whisk together for 5 minutes until pale and thick, stir in the melted chocolate and the cocoa powder, whisk the egg whites in a large clean until stiff then fold into the chocolate mixture until evenly combined.
3. Transfer the mixture to an oiled and lined 33*23 cm swiss roll, easing it well into the corners and spreading the surface level with a palette knife, bake in a preheated oven, 1800C set the timer for 20 minutes until risen and set.
4. Meanwhile, cover a clean damp tea towel with non-stick baking paper and sprinkle with a little caster sugar, quickly turn out the cooked sponge onto the paper, carefully peel off the lining paper and cover the sponge with a clean tea towel, leave to cool.
5. Make the filling, blend the chestnut puree and icing sugar in a food processor until smooth, transfer to a bowl and stir in the brandy, slowly whisk in the cream until light and fluffy, spread the filling over the sponge, leaving a 1 cm border all round, starting with a short side and using the paper, roll up the sponge to form a log, dust with icing sugar and serve.