1. Preheat oven at 180c.
2. In mixing bowl, whisk the egg whites until thick and peaking. While still whisking, gradually put in 1/4 cup of the castor sugar and continue whisking until the egg whites turns glossy, stiff peaks but not dry.
3. In a large bowl, whisk egg yolks and the remaining caster sugar until you get a mousy consistency, pale and thick.
Add in vanilla essence and sieve cocoa powder and fold both in gently.
4. Put in a dollop of egg white mixture into the yolk mixture and fold gently. Repeat until egg white mixture finish.
5. Line a baking tray (13” x 9”) with baking paper, leaving an overhang at the ends and sides.
6. Pour in cake mixture onto the baking tray and bake it for about 17-20 minutes.
7. When it is ready, role the hot cake length ways by using the baking paper and let it rest and cool. Don’t worry about and tears and dents this will be covered with icing later on.
8. Melt the chocolate either in microwave or put the chocolate into a heatproof bowl suspended over a pan of simmering water, set aside and let it cool.
9. Put in icing sugar into food processor and blitz til there’s no lumps. Add in butter and process until pale and smooth. Add the cooled chocolate and vanilla and pulse again until well combined
10. To assemble, unroll the cake and trim the edges. Spread some icing thinly over the cake , going right out to the edges. Re-roll the cake tightly pressing against the baking paper.
11. Cut one end on a slight angle and put the remaining on a long dish and place the cut piece against the side of the longer piece. That will be the branch part.
12. Spread the Yule log with the remaining icing covering the cut off ends as well as the branch. Create a wood-like texture by ,raking along the length of the log with a fork or a skewer.
Optional- you can dust the Yule log with some icing sugar this will make it look like fallen snow..