Hedgelog (Yule log)

Preheat the oven to 180°C/Gas Mark 4. Have ready a small saucepan of simmering water. Put the chocolate into a small heatproof bowl that will sit snugly on the pan without the base touching the water. Set the bowl over the pan and leave until the chocolate has melted, making sure it doesn't get too hot. Remove from the heat and set aside.

Meanwhile, place the egg yolks and sugar in a mixing bowl and beat, using a handheld electric whisk, for 5-6 minutes, until the mixture is pale lemon in colour. In another bowl, and using clean beaters, whip the eggs whites to firm peaks.

Add the melted chocolate to the beaten yolks and mix until evenly combined. Fold in the whisked egg whites, being careful not to lose too much of the incorporated air.

Spoon the mixture into the prepared tin and bake for 15-20 minutes or until the mixture is firm to the touch. Leave to cool for 5 minutes before covering with a slightly damp tea-towel (to prevent a crust from forming). Leave for several hours.

When ready to assemble, lay a piece of greaseproof paper on your work surface and dust with the icing sugar and cocoa mix. Remove the tea-towel from the cake and invert onto the paper. Remove the tin and baking parchment.

Spread about three-quarters of the chestnut purée onto the cake, leaving a clear margin of about 1.5cm along each edge. Using the paper as a guide, roll up the sponge like a Swiss roll. Place it, seam side down, on a cake board or plate. Shape one end of the cake to create a pointy hedgehog face.

Mix the remaining chestnut purée into the chocolate ganache and smother over the 'hedgelog'. Use the blade of a knife or a fork to prickle up the surface. Insert chocolate buttons for hedgehog spines, hazelnuts for eyes and the cherry for a shiny nose.