Chocolate yule log

Preheat the oven to 180°C/gas mark 4. Separate the egg yolks from the whites and place into separate large mixing bowls. Set the whites aside. Whisk the yolks with an electric whisk until creamy and fluffy, then whisk in the sugar for 1 min. Sieve the cocoa gradually into the mixture, mixing it in thoroughly with a wooden spoon each time. Whisk the egg whites for 3 mins, until standing in soft peaks. Add a third of the whites to the chocolate mixture and fold in. Repeat until all the egg whites are folded in. Stir in the chocolate drops. Pour the mixture into a 25 x 35cm rectangular baking tray, lined with baking paper. Bake in the preheated oven for 20-25 mins, until the mixture bounces back when lightly pressed. Allow to cool then remove from the tray and place on a wire rack. Once completely cool, sprinkle 2 tbsp of the brandy over the risen side of the cake and leave to soak. In a small saucepan, cover the cranberries with water and add 2 tbsp caster sugar. Bring to the boil, then simmer for 10 mins, until soft. Drain and refresh in cold water until cool. Drain again. Whip the double cream in a bowl until thick. Mix in the cranberries with just two whirls, to create a swirl effect. Layer the cake with the cream, leaving a border of 2cm. Using the baking paper to manoeuvre, roll the cake together into a roll lengthways. In a mixing bowl, cream the butter and icing sugar together until smooth and fluffy. Break 300g of the chocolate into a heat-proof bowl, and place over a pan of gently simmering water. Make sure the bowl does not touch the water. Stir occasionally until the chocolate is melted. Remove from the heat then stir until smooth. Mix into the butter mixture, along with the single cream and remaining brandy. Smooth onto the log with a spatula, filling the gaps to fix. Chill for 30 mins, then run a fork over the icing to make bark-like lines. Chill until needed. While the yule log is chilling, place the holly leaves on a plate and melt the remaining chocolate as above. Paint the top of the leaves with the chocolate and then chill for 20 mins. Repaint with the chocolate (the chocolate should still be malleable) and then chill the leaves for 1 hr. Carefully peel the chocolate leaves from the holly and position on the log. Dust with icing sugar and serve.