100驳/3陆辞锄 chocolate hazelnut spread (optional)
100驳/3陆辞锄 plain flour
戮 tsp baking powder
50驳/1戮辞锄 cocoa powder
100驳/3陆辞锄 hazelnuts, roughly chopped
50ml/2fl oz hazelnut liqueur (optional)
pinch salt
250g/9oz granulated sugar
300驳/10陆辞锄 dark chocolate, at least 70% cocoa solids
250g/9oz butter
4 free-range eggs