Please note that cooking time can be up to 8 hours depending on if you are using fresh or frozen berries as well as how hot your crockpot runs. Allow ample time - it is worth it!
Place blueberries in crockpot and cook on HIGH for 1 hour.
Stir blueberries and then cook on LOW for 1 hour.
If you wish a smoother blueberry butter, puree blueberries before continuing to next step with an immersion blender or remove, puree in a blender and return to the crockpot.
Cook on LOW for an additional 4 hours, keeping the crockpot propped open with a wooden spoon to allow the steam to vent. Stir your puree every hour to check consistency.
Once your blueberry puree has cooked down, add remaining ingredients. Replace the lid, again propped open and cook for an additional hour. If you still do not have the thickness you wish, increase temperature to HIGH and continue to cook and check every 30-45 minutes until you have the consistency you wish. Remember it will thicken slightly more upon cooling.
Remove and place in airtight containers. Blueberry butter, if not consumed in a flash, will keep in the refridgerator for 7-10 days. Freeze up to 6 months.