600g/1lb 5oz fresh blackberries, hulled
½ unwaxed lemon, finely grated zest only
1 tbsp fresh lemon juice
fresh mint leaves, to decorate
150²µ/5½´Ç³ú plain flour
½ tsp baking powder
150²µ/5½´Ç³ú caster sugar
2-3 tbsp caster sugar, to sweeten
50g/1¾oz blanched hazelnuts
75g/2½oz preserving sugar
125²µ/4½´Ç³ú butter, softened
300ml/10fl oz double cream, well chilled
100ml/3½fl oz plain natural yoghurt