Preheat the oven
to 180'C/350"F/Gas4. Base line and grease a 33 x
23cm/13 x 9in Swiss roll tin. Whisk the egg whites
until stiff. Beat in 30ml/2 tbsp of the caster
sugar.
Beat the egg
yolks with the remaining caster sugar and
15ml/1 tbsp water for about 2 minutes until
the mixture is pale and leaves a thick ribbon
trail.
Sift together the
flour and baking powder. Carefully fold the beaten
egg yolks into the egg whites, then fold in the
flour mixture.
Turn out onto a
piece of greaseproof paper lightly sprinkled with
caster sugar. Peel off the lining paper and cut off
any crisp edges. Spread with jam, if wished, and
roll up, using the greaseproof paper as a guide.
Leave to cool completely on a wire rack.