Based on a recipe first published in a slightly different form by Elizabeth David as a Chocolate and Almond Cake in French Provincial Cooking. It is rich, dense and slightly fudgy, but not as cloying as mudcake.
250g dark, bitter cooking chocolate
150g castor sugar
100g ground almonds
5 free-range eggs, separated
Heat oven to 180C. Melt chocolate, sugar and butter in a bowl over a pot of simmering water. Remove from heat, stir thoroughly to combine, mix in ground almonds, then beat in the egg yolks, one at a time.
Beat egg whites until stiff and peaked, and stir a couple of spoonfuls into the chocolate mixture to lighten it, before gently folding in the rest.
Turn into a buttered and floured 20cm round tin and bake for 40 to 50 minutes.
Leave to cool before removing from tin. Dust with icing sugar to serve.