• 100 g/4 oz butter
• 40 g/1½ oz cocoa powder
• 50 g/2 oz plain chocolate, broken into small pieces
• 2 medium or large eggs
• ½ level teaspoon salt
• 225 g/8 oz light muscovado sugar
• 50 g/2 oz self-raising flour
• 75 g/3 oz pecan nuts, roughly chopped (optional)

Preheat the oven to 180°C/350°F/gas mark 4. Butter a 17.5 cm/7 in square cake tin. Put the butter into a saucepan over a gentle heat and stir until melted. Stir in the cocoa powder until it is smoothly blended, then add the chocolate. Continue stirring until melted and then remove from the heat.

Put the eggs in a large bowl with the salt and sugar and whisk thoroughly until light and frothy. Then whisk in the butter and chocolate mixture. Sift the flour on to the mixture and fold in lightly with a large metal spoon. Stir in the chopped nuts, if using, and pour the mixture into the buttered pan. Bake in the centre of the oven for 30-40 minutes — it should still feel slightly undercooked. Cool in the tin, then cut into squares or oblongs and remove from the tin with a flexible spatula.