This is a very delicate cake which requires light handling.
Ingredients
- 25g (1oz) Cornflour
- 70g (2 1/2 oz) Plain Flour
- 2 tablespoons of good qualty cocoa powder
- 225g (8oz) Caster Sugar
- 1/2 Lemon
- 10 egg whites
- 2 pinches of salt
- 1 teaspoon of cream of tartar
For the Icing
- 50g (2oz) Plain or Bitter Chocolate
- 40g (1 1/2 oz) Butter
- 100g (4oz) Icing Sugar
- 4 tablespoons of milk
- 1 egg
- pinch of salt
- Vanilla Essense
Set the oven at Gas Mark 4 (180c or 350f)
Prepare a 25cm or 10inch springform cake tin with a ring mould capacity. Flour lightly (do not butter!).
Sieve the flour, cornflour, cocoa and half the caster sugar together into a bowl and resift twice more to make them really light. Hold the sieve as high over the bowl as possible.
Rub 2 large bowls with the cut surface of the lemon, and divide the egg whites between them. Add pinch of salt and a squeeze of the lemon juice to each. Whisk until light and fluffy (and begin to foam). Add half the cream of tartar, and whisk until they form firm peaks. Then whisk in half of the remaining caster sugar. Repeat with the second bowl of egg whites. When complete you should have a very stiff meringue mixture. Transfer both lots of whites into the largest bowl you have, making sure that the bowl is free of grease.
Sift some of the flour and cocoa mixture over the whites, covering the surface only very lightly, and fold in very carefully using a stiff spatula or metal spoon. You are trying to keep as much air in the eggs whites as possible.
Turn mixture into the prepared cake tin and run a knife around the edges. Smooth the top.
Bake in oven for 40 – 45 minutes, or until the top feels firm but springy.
Remove and invert over a wire wrack. Leave to cool thoroughly. Only then slide a knife around the edges and remove from the tin.
Icing
Melt the chocolate, add the butter and stir until smooth.
Put remaining ingredients into a bowl and whisk lightly until smooth. Add chocolate and butter mixture, and continue to whisk until bulky and smooth (5 minutes should do the trick using an electric mixer).
Slice cake in half, and fill middle with less than half of the icing. Spread the rest over the top.