Yule log

Start with the ganache. Bring the cream to the boil and add the chopped chocolate. Stir until the batter is completely smooth. Place in the fridge to harden a bit.

Make the vanilla filling. Place all ingredients except the butter in a saucepan. Let simmer for a minute or so, whisking constantly. Set aside and let the cream cool completely. 

Meanwhile, make the base for the swiss roll. Preheat the oven to 250°C on the top and bottom heat setting. 

Beat the eggs and soft brown sugar for a few minutes until the mixture is light and fluffy. 

Sift together potato flour, cocoa and baking powder and fold in carefully. Stir to make a smooth batter. Pour the batter onto a baking tray lined with baking parchment and spread it out to make an even layer. 

Bake the base in the middle of the oven for 4-5 min. 

Place a piece of baking paper on a clean kitchen towel. Sprinkle granulated sugar in an even layer on the baking parchment. Then take the base out of the oven and turn it over onto the baking parchment with the granulated sugar. Carefully peel off the old baking parchment and put on a new sheet. 

Carefully roll up the base in a tea towel as tightly as possible with the baking parchment underneath and on top. Leave to cool completely. 

Beat the vanilla filling with an electric whisk and add a little butter at a time. Beat for a few minutes, until the filling becomes fluffy. Spread it on the swiss roll and roll up from the short side. 

Take out the ganache before it becomes too firm and spread a thick, even layer around the swiss roll. Place in the fridge for about 10 minutes and then make marks with a knife so that it looks like a stump. Sprinkle with icing sugar.