150²µ/5½´Ç³ú plain flour
½ tsp bicarbonate of soda
50²µ/1¾´Ç³ú caster sugar
75²µ/2½´Ç³ú milk chocolate, broken into small pieces, plus an extra 25g/1oz to serve
25g/1oz miso paste
100g/3½oz light brown muscovado sugar
sea salt
75²µ/2½´Ç³ú dark chocolate, broken into small pieces, plus an extra 25g/1oz to serve
100g/3½oz salted butter, melted
1 large free-range egg