This recipe has very few ingredients and no common allergens. Nevertheless, it produces surprisingly smooth "ice cream" with just the right amount of sweetness, and the cinnamon perfectly complements the tartness of the cranberries.
Unlike some other thin-skinned fruit, such as grapes and blueberries, cranberries contain very little sugar and are thus unlikely to attract yeast and become covered with a yeasty white film. Whether you have a yeast allergy or not, though, you should wash your cranberries and throw away any that are not perfectly fresh and firm.
Place a large spoon and a container for the ice cream in the freezer. Puree cranberry mixture in a food-processor. Freeze, following the instructions for your ice cream maker. Use the prechilled spoon to scoop the ice cream into its prechilled container. Put directly into freezer to harden.