Another Elizabeth David recipe. There is a similar one in Don't Sweat the Aubergine; but hers is better. It's moist and gooey.
Unlike the recipe for cheese tart, this one needs only tiny adaptations -- except that it may take longer to set than she suggests. The cake in my book sits in a bain-marie; and I wonder if that method would cook this one more efficiently.
110 g dark chocolate
84 g butter
100 g caster sugar
2 tbsp flour
3 eggs, separated
Cut up the chocolate, and melt it in a ceramic bowl suspended above a pan of barely simmering water. Remove from the heat, and stir in the butter*, cut into pieces; when the butter has melted, stir in the sugar, flour, and egg yolks. Beat the egg whites until they form firm peaks. Fold them into the chocolate mixture. Pour the mixture into a buttered loaf tin -- mine, 7 cm x 16.5 cm, was just the right size.
Bake in a gas mark 4/180 C oven. Elizabeth David gives a time of 35 minutes; my cake took 10 minutes longer than that. A skewer inserted into the middle of the cake should emerge clean.
When cool, turn out the cake on to a rack. I wrapped it in a layer of greaseproof paper, then foil.
*Update, 19/11/11: This cake, delicious when fresh, becomes compacted after a day or so. I tried introducing extra lightness by creaming the butter and sugar first; then I stirred in the chocolate, flour, and egg yolks. It produced a better result.