This is one of those really old-fashioned cakes that I've not made since domestic science at school and thought would be easy, but actually, there's a lot here that can go wrong.
But as we're going to be away for Christmas and we were having a little neighbours' tea party yesterday, I thought I'd give it a go. I like to have everything sorted the day before but this really has to be eaten on the same day. I didn't enjoy the risk of making it on the morning of the party and although it was a bit of a faff and me and melted chocolate don't get on so well, it was a big hit and the icing covers a whole lot of cracks! Have a go!
75g self raising flour
1 tsp baking powder
100g golden caster sugar, plus a little extra for sprinkling
5 large eggs
FOR THE FILLING
icing sugar, to taste
splash of double cream
FOR THE ICING
200ml double cream, broken into pieces
200g dark chocolate
1 Preheat the oven to 190C / Gas 5. Line a 30x40cm Swiss roll tin with baking parchment and rub with a little butter.
2 Sift the flour, cocoa and baking powder into a bowl. In a second bowl, whisk the sugar and eggs until thick and airy – they should roughly triple in volume. Sift over the flour mixture and gently fold in, making sure there are no pockets of flour hiding in the bottom of the bowl.
3 Pour into the tin as evenly as possible then bake for 10 – 12 minutes until just firm to the touch. Sprinkle some sugar onto a sheet of baking parchment and turn out the sponge. Peel off the paper then roll it up with the new sheet of paper inside. Leave to cool completely.
4 Make the icing. Pour the cream into a small and bring to the boil. Add the chocolate and stir to melt. Leave to cool completely then chill until thick enough to spread – keep your eye on it as it cools - it’s runny for ages then suddenly changes from runny to thick to too-thick-to-spread in quite a short time.
5 Make the filling: beat the mascarpone with a wooden spoon to soften a little then add icing sugar to taste – it may be a little to thick to spread so a little cream to soften.
6 Open out the sponge and spread with the mascarpone mixture, if you like, grate over some chocolate then roll up. Cut a diagonal slice off and place next to the log to look like a branch. Spread with the chocolate icing in a wood-like pattern and leave to set. Dust with icing before serving.