150驳/5录辞锄 plain flour
1 tsp bicarbonate of soda
75g/2陆oz light brown sugar
50g/2oz caster sugar
30g/1oz cocoa, sifted
陆 tsp salt
1 tsp vanilla extract
125g/4oz dark chocolate
350驳/12录辞锄 dark chocolate chips
125g/4oz unsalted butter, softened
1 free-range egg, cold from the fridge