If Blueberry Jam and Apple Butter had a baby, they would make Blueberry Butter! So yummy!
Add blueberries into the slow cooker and set cooker on high for 90 minutes.
Take off the lid and cook for another 30 minutes on low.
Use a hand blender or immersion blender to puree the blueberries right in the slow cooker.
Put the lid back on the slow cooker leaving it slightly cracked to allow air to escape. Cook for another 3 hours on low. Stir every hour.
Next stir in the brown sugar, lemon juice, cinnamon, nutmeg, and allspice until combined.
Replace the lid, again leaving a small crack in the lid to allow air to escape. Over the next hour, the blueberry butter should thicken to your desired consistency.
Pour butter into clean jars and allow to cool before refrigerating. If canning, water bath can jars with 1/2 inch headspace for 15 minutes.
This recipe yields 4 cups or about 2 pints of Blueberry Butter.