Instructions:
1. Rinse the blueberries and drain any excess water.
2. In a slow cooker, combine the blueberries, sugar, butter, lemon zest, cinnamon, and vanilla extract.
3. Cook on low heat for 6 to 8 hours, stirring occasionally, until the mixture is thick and the blueberries have broken down.
4. Use a hand-held blender or immersion blender to puree the mixture until it is smooth.
5. Return the mixture to the slow cooker and continue cooking on low heat for 2 to 4 hours, stirring occasionally, until the mixture has thickened to a spreadable consistency.
6. Allow the blueberry butter to cool completely, then transfer it to an airtight container.
7. Store in the refrigerator for up to 2 weeks.
Enjoy your homemade slow cooker blueberry butter spread on toast, muffins, or biscuits for a delicious and healthy breakfast treat!
