Put all the ingredients in a crockpot and stir to combine well. Turn on high. Let it cook for about 2 hours or until the cranberries are soft. Remove the cinnamon stick and puree the mixture in a food processor. Do this in two batches. Be careful as the mixture is hot, I cover the top opening of the machine with a dish cloth. Let the machine run for a full minute to puree the cranberries very finely. Force the cranberry puree through a mesh sieve or strainer. Push forcefully with the back of a spoon to get as much cranberry puree as you can. Discard the solids. Pour the puree back into the crockpot. Turn the crockpot to high, and leave the lid ajar. Cook until thickened, approximately another 2 hours, stirring occasionally. Put the cranberry butter into clean jars with tight fitting lids and let cool. Store in the refrigerator and consume within a month. If you would like to can this recipe, spoon the hot mixture into sterile jars and boil in a water bath canner for 10 minutes. Makes about 2 cups.