Chocolate Sponge Cake - egg yolks

Method

• Combine the egg yolks and sugar in top of double boiler. Heat over hot water while whisking until sugar is disolved and bright yellow. (Use electric hand mixer if you prefer).
• Put into a stand mixer and mix with paddle attachment on high until the egg/sugar mixute forms ribbons (this is a sabayon).
• Dissolve cocoa in water and mix to a paste.
• Combine the flour and 1/2 of the salt.
• Whip egg whites in a separate bowl with 1/2 of the salt. Start on low until the eggs foam, then continue on high until they reach soft peak stage. Add sugar and reduce mixer to medium speed.
• Put the sabayon into a large clean bowl and add cocoa paste. Combine well. Fold 1/2 the flour into the chocolate mixture. Lighten with a bit of egg whites. Add remaining flour. Incorporate. Add 1/2 of the remaining egg whites. Fold in the rest of the egg whites.
• Spread with an offset spatula into a 1/2 sheet pan that has been lined with parchment paper. Sweep the edges of the pan with your thumbs to remove any excess batter.
• Bake at 350 degrees for approximately 10 minutes until it springs back when pressed lightly.
• Sprinkle 2 oz powdered sugar over clean kitchen towel. Remove cake from pan by losening any edges with a sharp knife and pulling up parchment. Turn onto sugared kitchen towel. Remove parchment paper and roll cake jelly roll style into towel while warm. Rest in towel for approximately 10 minutes.
• Unroll and fill with desired filling.