Preheat oven to 350 deg F, (Gas mark 4 or 180 deg C).
Line a nine inch cake tin with greaseproof paper and grease the tin.
Break the chocolate into small pieces and melt it with the butter over hot water.
Beat the egg yolks with half the sugar.
Fold in the melted butter and choc mix
Fold in the ground almonds.
Beat the egg whites until frothy, gradually add the remaining sugar, beating until stiff peaks form.
Fold in the beaten egg whites.
Bake at 350 deg F until a wooden pick comes out clean, approx 40 minutes
Serve with whipped cream dusted with cocoa powder, the cake may be dusted with powdered sugar