50gramsdark chocolate, melted and cooled to room temperature (or you can use a combination of dark and semi-sweet or milk or white)
INSTRUCTIONS
Preparation
Preheat the oven to 170 degrees Celsius. Butter a 10-inch baking pan and line the bottom and sides with baking parchment. Rub the baking parchment lightly with a layer of vegetable oil. Set the baking pan aside.
Egg Yolk Batter
Place the egg yolks and sugar in a large bowl. Beat with an electric mixer until thick and pale. Add in water, vegetable oil and vanilla and beat it in. Sift in 60 grams of plain flour and 10 grams corn flour and beat it in till the batter is thick and leaves a trail when you lift up the beaters. Scoop 1 tablespoon of the egg yolk batter into a small bowl and fold in 1/2 teaspoon plain flour. Sift the cocoa powder into the large bowl of egg yolk batter and fold it in.
Place the egg white in a clean, large bowl (dry and oil-free) and beat until the egg white is foamy. Add in the pinch of corn flour and beat until the egg white forms stiff peaks. Fold 2/3 of the egg whites into the small bowl of egg yolk batter. Fold the remaining egg white into the large bowl of egg yolk batter.
Transfer the small bowl of egg yolk batter into a piping bag. Pipe a log design onto the baking parchment. Bake for 2 minutes until the batter has dried up slightly. Set aside on a wire rack.
Egg White Batter
Place the egg whites in a large bowl (you can use the same bowl used to beat the egg white previously) . Beat with an electric mixer till foamy. Add in the sugar and corn flour and beat till stiff peaks formed. Fold the stiff egg whites into the egg yolk batter in 3 parts until no trace of egg whites is left.
Transfer the batter onto the baking pan and spread it evenly. Rap the baking pan 2 to 3 times on the table counter to get rid of excess air bubbles. Bake for 15 to 20 minutes until the genoise bounced back slightly when touched or when a skewer inserted into the centre of the genoise comes out clean.
Invert the genoise out onto a large baking sheet. Peel off the baking parchment and turn the genoise right side up. Roll up the genoise and leave it to cool completely on a wire rack.
Chocolate Mousse and Assembly
Fold the whipped cream into the melted and cooled chocolate.
Unroll the genoise, spread it with chocolate mousse and roll it up. Refrigerate till the log cake is well-chilled. Dust with icing sugar and serve.
NOTES
adapted from Junko's Swiss Rolls (see here for a review of the cookbook) (The above link goes to a website where the blogger does a review of Junko's cookbook, the cookbook is in Japanese and no translation is available. I got mine when I was in Taiwan and it was a translated copy in Chinese. I've not seen an English copy around, if you know where to get it, do let me know!)