Method

• 1.
  Preheat oven to 180°C. Grease a 28cm x 39cm lipped-edge baking pan or Swiss roll pan and line with baking paper along the longest sides, leaving 2cm overhanging.

• 2.
  Place egg yolks and caster sugar in a stand mixer fitted with the whisk attachment and whisk until thick and pale. Fold through cocoa and flour, then add chocolate and milk, and fold to combine.
• 3.
  Clean stand mixer, add eggwhites and whisk to soft peaks. Fold one-quarter eggwhite into chocolate mixture, then carefully fold through remaining eggwhite
• 4.
  Pour cake mixture into prepared pan and smooth to edges. Bake for 12 minutes or until cake springs back when gently pressed.
• 5.
  Meanwhile, place a clean tea towel on a work surface with a long edge facing you and, using a fine sieve, dust all over with half extra cocoa.
• 6.
  Working quickly, invert hot cake onto prepared towel and remove baking paper. Roll tea towel away from you to form a log and set aside, rolled, until cake is completely cool.
• 7.
  Meanwhile, whisk creme fraiche and icing sugar together to firm peaks.
• 8.
  Carefully unroll cake (it may crack slightly; this is fine) and spread with creme fraiche mixture. Scatter over half the raspberries, carefully re-roll and dust with remaining extra cocoa. Serve with remaining raspberries.