250g/9oz plain flour, plus extra for dusting
1 tbsp demerara sugar, for sprinkling
50驳/1戮辞锄 roasted hazelnuts, chopped
25g/1oz icing sugar, plus extra for dusting
陆 tsp salt
100驳/3陆辞锄 dark chocolate (minimum 70% cocoa solids)
250g/9oz very cold unsalted butter, cut into cubes
200ml/7fl oz double cream
50驳/1戮辞锄 mascarpone
2 tbsp instant coffee, mixed with 1 tbsp boiling water to make a paste
1 free-range egg, beaten for egg wash