METHOD
1. Preheat the oven to 230C/450F/gas 8. Prepare a Swiss roll flat tin or similar, 23 x 30cm, by lining it with baking parchment.
2. Separate two of the three eggs; place the two egg whites in one bowl and the two yolks and the whole egg in another. Add the 66g caster sugar to the egg and yolks and beat on high speed for about five minutes until pale and fluffy and ribbons form over the surface when the beaters are lifted. Add the vanilla extract and beat in.
3. Mix the flour with the corn flour and sift over the egg mixture in two goes, folding it in gently with a spatula after each addition.
4. Change the mixer attachment to a whisk (balloon on the standing mixer) and beat the egg whites until foamy, add the cream of tartar and beat until soft peaks form. Gradually add the 10g of sugar and beat until the mixture forms stiff peaks (a good trick is to turn the bowl upside down – if the egg whites stay in, they’re done. If they fall out, you have to start over again…).
5. Fold a small amount of the egg whites into the egg yolk mix with a spatula, to loosen it up. Then add the rest of the egg whites and fold carefully not to deflate it, small streaks of white are acceptable. Pour it into the prepared tin smoothing the surface with a spatula. Bake for 6 – 8 minutes, when you press the surface with your finger, it should spring back. It will have puffed up considerably.
6. Remove from the oven and immediately sprinkle generously with icing sugar, cover with a clean tea towel and invert the cake onto the towel. Peel the parchment off carefully, sprinkle with icing sugar and roll up tightly from the long side, helping yourself with the towel. Place on a wire rack to cool.
7. If using frozen raspberries, thaw them completely and drain the excess moisture on paper towels. Pour the cream into a clean (preferably also chilled) bowl, add the sugar and beat to soft peaks. Fold the raspberries in gently, so that the cream is streaky but some chunks remain.
8. Unroll the sponge and spread the cream over it evenly with a spatula. Re-roll the sponge as tightly as you can and place on a serving tray, dust with more icing sugar before serving.