Bûche de Noël (Yule Log Cake)

The Bûche de Noël cake is a French Christmas tradition that dates back to the 19th century. 

INGREDIENTS

FOR THE CAKE
Cooking spray
6 large eggs, separated
65 g plain flour
30 g unsweetened cocoa powder
150 g caster sugar, divided
1/4 tsp. salt
Icing sugar, for sprinkling

FOR THE FILLING
240 ml double cream
65 g icing sugar
1 tsp. vanilla extract
Pinch salt

FOR THE FROSTING AND DECORATING
110 g butter, softened
250 g icing sugar, plus more for garnish
30 1/4 g cocoa powder
1/2 tsp. vanilla extract
2 tbsp. double cream
Pinch salt
Chocolate curls, for garnish
Cranberries, for garnish
Small rosemary sprigs, for garnish

METHOD

1. Preheat oven to 180°C (160ºC fan). Line a Swiss roll tin with parchment paper and grease with cooking spray. In a medium bowl mix together flour, cocoa powder, and salt.
2. In a large bowl beat egg yolks until thick. Slowly add 100g sugar and beat until pale then beat in flour mixture.
3. In another large bowl beat egg whites until soft peaks form. Add remaining sugar a little at a time and continue to beat until stiff peaks form. Gently fold egg whites into batter in two batches.
4. Pour batter into prepared pan and spread into an even layer. Bake until top springs back when lightly pressed, 12 minutes.
5. Dust a clean kitchen towel with icing sugar and invert warm cake onto towel. Peel off parchment paper.
6. Starting at the short end, use the towel to tightly roll cake into a log. Let cool completely.
7. Make filling: In a large bowl beat together double cream, icing sugar, vanilla extract, and a pinch of salt, until stiff peaks form. Refrigerate until ready to use.
8. When cake is cool, unroll and spread filling evenly over cake. Roll cake back into a log, this time without towel. Place seam side down on a baking tray and refrigerate until well chilled, 1 hour.
9. Make frosting: In a large bowl beat butter until smooth. Add icing sugar and cocoa powder and beat until no lumps remain then beat in vanilla, double cream, and salt.
10. When ready to serve, trim ends and frost cake with chocolate buttercream. Dust lightly with icing sugar and top with chocolate curls. Place cranberries and rosemary on log to create mistletoe.