In a large mixing bowl add the melted butter and sugars and stir to mix together.

Add the egg and mix well. Sift in the flour, bicarb, xanthan gum and cinnamon and mix together using a wooden spoon. It should form a thick, sticky dough.

Add the oats and raisins and mixed together until fully combined and the raisins are evenly distributed.

Break off golf-ball sized pieces and roll into a ball - or use an ice-cream scoop to scoop equal amounts of dough before rolling them into a ball shape. Place on a lined baking sheet, and refrigerate for at least one hour.

When ready to bake, preheat the oven to 180'C / Fan 160C / Gas Mark 4 and line two baking sheets with baking paper.

Place 4-5 cookies on a tray with plenty of room between them. Bake for 12-15 minutes until golden. (You may find you need to do this in several batches). Remove from the oven and cool on the tray for 5-10 minutes until firm enough to move onto a wire rack to cool completely.