Preheat the oven
to IS0'C/350"F /Gas 4. Sift both flours into a bowl.
Whisk the egg
whites in a large grease-free bowl until very
stiff, then gradually add the sugar and vanilla
essence, whisking until the mixture is thick and
glossy.
Fold in the flour
mixture with a large metal spoon. Spoon into an
un-greased 25cm/10in angel cake tin, smooth the
surface and bake for 40-45 minutes.
Sprinkle a piece
of greaseproof paper with caster sugar and set an
egg cup in the centre. Invert the cake tin over the
paper, balancing it carefully on the egg cup. When
cold, the cake will drop out of the tin. Transfer it
to a plate, dust generously with icing sugar and
serve.