This recipe is derived from one in an old M&S ‘Chocolate Cookery” book that Jennie gave me in Sheffield in 1984. The freezer dough method works very well for gluten-free as it makes the dough manageable even though it is very crumbly. Numerous variations exist from simply forgetting the swirling and making them one flavor, to substituting ginger or cinnamon for the cocoa, or orange rind for the lemon rind. Alternatively add 2oz of nuts instead of 2oz of flour, or 2oz of oats or oatmeal instead of 2oz of flour. If you’re really after a great swirled appearance then try rolling out each piece of dough and then placing them on top of each other before rolling them up, but this is much harder with gluten-free dough.