Preheat your oven to 180°C (or 160°C for fan ovens). Grease a 23x33cm swiss roll tin and line it with parchment paper.

In a large mixing bowl, beat together 5 large eggs and 100g of caster sugar on high speed until thick and pale, about 5-7 minutes. Fold in 1 teaspoon of vanilla extract.

Sift together 60g of plain flour and 40g of cocoa powder. Gently fold this mixture into the egg-sugar mixture using a spatula.

Pour the batter into the prepared tin, spreading evenly. Bake for 12-15 minutes until the sponge springs back when lightly pressed.

Invert the sponge onto a piece of parchment paper dusted with icing sugar and roll it up while still warm. Cool completely.

Heat 400ml of double cream in a saucepan until just below boiling. Pour over 300g of chopped dark chocolate and 100g of milk chocolate. Stir until smooth and let cool.

Whip 300ml of double cream with ½ tablespoon of icing sugar until soft peaks form. Fold in 2-3 tablespoons of Baileys Irish Cream if desired.

Once the sponge is cool, unroll it and spread an even layer of whipped cream over the surface. Roll up tightly again.

Transfer the Yule Log to a serving plate, cut an angle from one end, pipe or spread the ganache over the log, and dust with icing sugar before serving.