Bûche de Noël

Ingredients

• For the sponge:
• 50g cocoa
• Pinch of sea salt
• 3 large free-range eggs
• 75g light muscovado sugar
• Icing sugar, for dusting
• Butter, for greasing
• For the filling:
• 100g dark (70% cocoa solids) chocolate, broken into pieces
• 375g unsweetened chestnut purée
• 60g light muscovado sugar
• 11/2 teaspoons vanilla extract
• 180ml whipping cream

Method

1. To make the sponge, preheat the oven to 200°C/gas mark 6. Butter a 23 x 32cm swiss roll tin, line it with baking paper and butter this also.
2. Sift the cocoa into a bowl and add the salt. Place the eggs and muscovado sugar in a bowl and whisk for 8–10 minutes, using an electric whisk, until the mixture is pale and mousse-like. Lightly fold in the cocoa in two goes.
3. Pour the mixture into the prepared tin and smooth it using a palette knife. Give the tin a couple of sharp taps on the work surface to eliminate any large air bubbles and bake the sponge for 8–10 minutes, until set and springy to the touch.
4. Lay out a clean tea towel and sift over a fine layer of icing sugar. Turn the cake out on to it and carefully roll it up with the tea towel, leaving the paper in place, starting at the short end so you end up with a short fat roll. Leave to cool for 40–60 minutes.
5. To make the filling, gently melt the chocolate in a bowl set over a pan of simmering water, then set it aside to cool to room temperature. Cream the chestnut purée, sugar and vanilla in a food processor, then add the chocolate. Whip the cream until it forms soft peaks, and fold it into the chocolate chestnut mixture in two goes.
6. Carefully unroll the sponge and peel off the paper parchment. Spread with half the chocolate chestnut mousse, then roll the sponge up again and tip it on to a long serving plate, seam downwards. You could also line a small board with silver foil and decorate the edge. Smooth the
7. rest of the filling over, then make lines along its length with a fork, swirling the ends to create a log effect, and making a few knots on the log too.
8. Chill the roulade for an hour; if keeping it for longer than this, loosely cover it with clingfilm and bring it back up to room temperature for 30 minutes before eating.
9. Shortly before serving, shower the log with icing sugar or edible glitter.