400g/14oz smooth peanut butter (the regular kind, not a health-store variety)
225g/8oz plain flour
1 tsp baking powder
½ tsp bicarbonate of soda
100g/3½oz soft dark brown sugar
125²µ/4½´Ç³ú caster sugar
50²µ/1¾´Ç³ú cocoa powder
600g/1lb 5oz icing sugar
30g/1oz dry roasted peanuts, chopped, to decorate
½ tsp fine sea salt
2 tsp vanilla extract
200g/7oz unsalted butter, plus extra for greasing
300g/10½oz unsalted butter, softened
120ml/4fl oz double cream
2 large free-range eggs, at room temperature