Chocolate Swiss Roll

1. Preheat oven to 180 degrees C. Line a medium baking tray with ungreased baking paper or well-greased waxed paper,
allowing the paper to extend over the edges. Separate the eggs, beat egg whites until stiff and set aside.
2. Beat together the egg yolks and castor sugar until thick and pale yellow, gently beat in the water and vanilla essence.
3. Sift together the flour, baking powder, cocoa powder and salt. Sift again into the egg mixture.
4. Beat until well combined, add the egg whites, fold in gently until well blended. Spoon batter onto baking tray evenly, filling right to the corners. Bake for 12-15 minutes, until the sponge is just firm to the touch.
5. Sprinkle a clean tea towel with water, and roll to dampen all over, place onto a worktop, sprinkle with castor sugar. Turn
the cake onto the tea towel, remove the tray and cover the cake with another damp cloth (do not remove the paper).
Leave for about 5 minutes for the steam to soften the edges of the cake. Carefully peel off the paper. Roll up and allow to cool, while wrapped in the cloth.