10 oz dark chocolate, broken in pieces
5 oz unsalted butter
6 eggs
1¾ oz caster sugar
Preheat the oven to 180°C – gas mark and lightly grease and line the base and sides of an 8” spring-form cake tin with greaseproof paper
Melt the chocolate and butter in a heatproof bowl set over a pan of simmering water being careful not to allow the bowl to touch the hot water.
Separate the eggs and whisk the yolks with 2 level tablespoons of the sugar until pale and smooth, then stir in the melted chocolate and mix well.
Beat the egg whites and remaining sugar until stiff and using a large metal spoon, quickly fold a third of the whites into the chocolate mix to slacken the mixture, and then gently fold in the remainder.
Pour the mix into the prepared cake tin and place on the middle shelf of the preheated oven for 20 minutes.
Remove from the oven and leave to cool in the tin for a few minutes. Transfer the cake to a wire rack to cool completely, then slice and serve .