Poor Disenchanted, I can't let you go unanswered. I've made this and Nigel Slater is to be Trusted. I didn't have golden caster sugar so used ordinary.
I reckon it would be even nicer with some choccy ganage (melt choc in double cream and whip when cool) or whipped cream on the side.
The perfect chocolate cake
By Nigel Slater
This works as teatime cake or dessert, though if using it for the latter, serve some raspberries on the side.
Serves 10
200g fine dark chocolate (70% cocoa solids)
a small, hot espresso
200g butter
80g plain flour
1 tsp baking powder
2 level tbs very good-quality cocoa powder
125g ground almonds
5 eggs
200g unrefined golden caster sugar
You will need a shallow cake tin, 23-24cm in diameter, about 5cm deep, the base lightly buttered and lined with a round of baking parchment. Set the oven at 180C/gas 4. Break or chop the chocolate into small pieces and melt it in a bowl resting over a saucepan of gently simmering water. As soon as it has started to melt, pour the hot espresso over the chocolate. Cut the butter into chunks and drop it into the chocolate and coffee. Resist the temptation to stir. Sift the flour, baking powder and cocoa together.
Separate the eggs, dropping the whites into a large bowl. Whisk the whites till they are thick and stiff, then quickly but gently fold in the sugar with a large metal spoon. Remove the chocolate from the heat and stir to dissolve the last of the butter. Mix the egg yolks, then stir them into the chocolate until the ingredients come together. Fold into the egg white and sugar. Lightly fold in the flour and cocoa mixture, then the ground almonds. Don't over-mix or knock the air out. Transfer the mixture to the cake tin and bake for 25 minutes. Test the cake with a skewer. It should come out clean. Leave to cool before turning out and slicing.