Use a cake tin with a loose bottom of about 20 cm.
- 300 g dark chocolate
- 350 g (380 ml) butter
- 4 eggs, separated
- 220 g (260 ml) caster sugar
- 300 g walnuts, finely chopped
Preheat oven to 160 °C. Line pan with baking paper and grease or spray it well. Melt chocolate and butter in a bowl over boiling water. Beat egg yolks and caster sugar until light and creamy. Add the chocolate and butter mixture. Fold in the walnuts. Beat egg whites until stiff and fold in. Pour mixture into pan and place on a baking tray. Bake for 10 minutes. Reduce heat to 150 °C and bake for another hour and 15 minutes. Leave to cool in pan. Sift icing sugar on top for decoration.