01 -
Add the blueberries, brown sugar, honey, lemon zest, lemon juice, cinnamon, and nutmeg to your slow cooker. Stir everything together until well combined.
02 -
Cover the slow cooker with its lid and cook on high heat for 1 hour. This helps the blueberries break down and release their juices.
03 -
Carefully transfer the hot blueberry mixture to a blender and blend until smooth. You may need to do this in batches depending on your blender size. Be cautious when blending hot liquids!
04 -
Pour the blended mixture back into the slow cooker. Prop the lid up slightly with a wooden spoon handle or chopstick. This allows steam to escape so the mixture can thicken properly.
05 -
Cook on low heat for an additional 4-5 hours, stirring occasionally if possible. You'll know it's done when the mixture has thickened significantly and coats the back of a spoon.
06 -
Once your blueberry butter has reached the desired thickness, ladle it into clean 8oz mason jars while it's still hot. Leave about ¼ inch of space at the top of each jar.
07 -
Let the jars cool completely before putting the lids on and storing in the refrigerator. Your blueberry butter will keep for up to 2 months in the fridge.