This is my mother's chocolate cake recipe; it's somewhat rich for me so I've never made it, but I know the recipe works.
8 oz plain chocolate, melted (she used Cadbury's Bourneville - any good-quality dark chocolate would work)
5 eggs, separated
4 oz butter
6 1/2 oz caster sugar (superfine sugar in the USA?)
3 oz ground almonds
1 1/2 oz self-raising flour
Whip egg whites until stiff
Cream fat and sugar
Add melted chocolate and egg yolks, and mix
Fold in nuts and flour
Gently fold in the beaten egg whites
Put into a well-greased 8" cake tin (one of the deep ones, not one for layer cakes), and bake at 350 degrees for about an hour.
When cold (preferably the next day), slice the cake through the middle and spread with a thin layer of apricot jam. Sandwich back together, and coat with chocolate covering (not sure about the recipe for this, but I know it involved more Bourneville).