200g/7oz plain flour
30g/1oz plain flour, sifted
½ tsp baking powder
50g/1¾oz soft brown sugar
100²µ/3½´Ç³ú caster sugar
30g/1oz cocoa powder
125²µ/4½´Ç³ú shelled hazelnuts, ground roughly in a food processor
240g/8½oz good-quality milk chocolate
pinch salt
125²µ/4½´Ç³ú dark chocolate (70% cocoa solids)
300²µ/10½´Ç³ú dark chocolate (75-80% cocoa solids)
175g/6oz butter, plus extra for greasing
125²µ/4½´Ç³ú unsalted butter
2 free-range eggs, 1 whole, 1 yolk only