Method

​1 First cream the butter, sugar, salt and vanilla extract together using an electric hand whisk. Mix in the 100g gluten-free flour really well to create a soft dough.

2 Now split the mixture in half. Add 10g of sifted cocoa powder to one half and knead in well and 10g gluten-free flour to the other half. Wrap the dough balls in clingfilm and put in the fridge for 30 minutes to firm up.

3 Take 2 sheets of baking parchment 20 x 12cm. Roll out each ball of dough onto a piece of parchment using a floured rolling pin till it is the same size as the paper. Pick up the paper with the chocolate dough on and flip it over on top of the plain dough, then peel off the paper.

4 Using the baking parchment to help you, with the longest side facing you, roll it up like a Swiss roll. Wrap it up in the parchment paper and pop back in the fridge for another 30 minutes to firm up again.

5 Once chilled slice into 1 cm wide pieces and place onto baking parchment, lie them flat on a baking tray. Bake in a preheated oven at 180°C/fan 160°C/gas mark 4 for 15-20 minutes until slightly coloured and just firm to the touch.

6 Allow the biscuits to cool completely on the tray. Then store in an airtight container. For best results though I recommend eating fresh on the day.