01 -
Place fresh blueberries into the pitcher of a blender or the bowl of a food processor. Blend until smooth to create a puree.
02 -
Transfer the blueberry puree to a 6-litre or larger slow cooker. Add the granulated sugar, ground cinnamon, freshly squeezed lemon juice, and lemon zest. Stir thoroughly to combine.
03 -
Cover the slow cooker and cook on low heat for 1 hour.
04 -
After 1 hour, prop the slow cooker lid open slightly with a wooden spoon or heat-safe utensil. This allows excess moisture to evaporate.
05 -
Continue to cook on low for an additional 4 to 5 hours, stirring occasionally. Check every hour until the mixture thickens and mounds easily on a spoon without running.
06 -
Once the blueberry butter reaches the desired consistency, ladle it into sterilized 500 ml canning jars or food storage containers. Cool completely, then refrigerate for up to 2 months or freeze for up to 1 year.