100驳/3陆辞锄 caramel
130驳/4戮辞锄 plain flour
280g/10oz caster sugar
20驳/戮辞锄 cocoa powder
pinch rock salt
250g/9oz dark chocolate, minimum 70% cocoa solids, broken up or roughly chopped
100驳/3陆辞锄 white chocolate, finely chopped
250g/9oz salted butter, plus extra for greasing
4 free-range eggs