This chocolate Swiss roll is our easier and lighter version of a Christmas Yule log. It is the perfect way to finish off a festive feast.
Preheat the oven to 180C/160C Fan/Gas 4. Line a 22x32cm/9x13in Swiss roll tin, or tall-sided baking tray with baking paper and lightly grease with butter.
Whisk the egg yolks and sugar together in a bowl until thick. Sieve over the cocoa powder and whisk in until full incorporated.
In a clean glass bowl using clean beaters, whisk the egg whites until stiff. Fold them into the cocoa mixture a spoonful at a time. Pour the mixture into the baking tin and spread out evenly. Bake for 20 minutes. Use a knife to cut the edges away from the tin, then leave to cool.
Turn the Swiss roll out on to a sheet of baking paper. Whisk the double cream, then fold in the crème fraiche. Using a spatula, spread this over the sponge. Sprinkle over the raspberries. Roll up from one of the short sides.
Melt the dark chocolate in a microwave or in a bowl over a pan of boiling water. Drizzle the chocolate over the top of the cake.