1. Oven temperature: 190°C/375°F/Gas Mark 5
2. Cream together the butter and the sugar and beat in the egg yolk. Gradually fold in the Gluten-Free Mix - the mixture will be quite crumbly at this stage. Bring the mixture together to form a dough; knead the dough for a couple of minutes until smooth on a surface lightly dusted with Mix.
3. Roll out the dough and cut out 12 rounds with a 5cm (2”) cutter and place on a baking tray. Lightly press a square of chocolate into the middle of each round. Cut out 12 rounds with a 6cm (2¼”) cutter and use to cover the chocolate, pressing the edges down lightly.
4. Bake in a pre-heated oven for 12-15minutes until golden. Allow to cool slightly before transferring to a cooling rack. Dredge with icing sugar to serve.

For an alternative, try using milk or white chocolate in place of plain or replace 25g Gluten-Free Mix with 25g cocoa to make double chocolate cookies!