1.Beat butter, extract, sugar and egg in small bowl with electric mixer until combined. Stir in ground hazelnuts, then sifted flour and cocoa.
2.Divide dough in half; roll each half between sheets of baking paper until 3mm (¹/ 8-inch) thick. Refrigerate 30 minutes.
3.Preheat oven to 180°C/350°F. Line oven trays with baking paper.
4.Cut dough into 4cm (1½-inch) fluted rounds; place on trays 2.5cm (1 inch) apart. Bake about 8 minutes. Cool on trays.
5.To make choc berry filling, beat cooled chocolate, butter and spread in small bowl with electric mixer until thick and glossy. Fold in raspberries.
6.Spoon choc berry filling into piping bag fitted with 2cm (¾-inch) fluted tube. Pipe filling onto flat side of half the biscuits;
Unfilled biscuits will keep in an airtight container for up to a week. Filled biscuits will keep for a few days in an airtight container in the fridge.Note