Preheat oven to 190°C/375°F/Gas Mark 5. Grease a baking tray (size) and sprinkle a little flour on it. Sieve flour with salt, soda bicarbonate and cream of tartar. Add rolled oats and cinnamon powder and mix.
Cream butter and Sugar Free well. Add the flour mixture and mix well. Add milk and vanilla essence and mix into a dough. Chill the dough wrapped in a piece of greaseproof paper for about an hour in a refrigerator.
Divide the dough into one inch diameter balls and flatten them well between the hands. Place them on the greased and floured baking tray, keeping sufficient distance between each.
Bake in the preheated oven for about fifteen minutes. Turn them onto a wire rack to cool. Store in an airtight tin.