For the Yule Log do you let the sponge cake cool before putting the buttercream on it? If so, how do you roll it without it breaking up?
Nigella's Yule Log (from NIGELLA CHRISTMAS) is a gluten-free chocolate sponge cake that is filled and coated with a chocolate buttercream. In the recipe the cake is made first and left to cool covered with a clean tea towel. The tea towel should help the sponge to cool without drying out, keeping it soft and making it easier to roll.
The sponge needs to cool to room temperature before the buttercream is added, as otherwise the buttercream will just melt and run out of the sponge as it is rolled up. You can use the parchment to help to roll the cake. The cake is gluten free it so may crack slightly but as it will be coated in buttercream after rolling this is not a big problem as the cracks should be hidden.