From Food in Jars:
- 8 cups of pureed blueberries
- 2 cups sugar
- 1 lemon, zested
- 2 teaspoons cinnamon
- 1/2 teaspoon grated nutmeg
- Put the pureed blueberries in a slow cooker.
- Place a lid on the pot and turn it on to low.
- After about an hour, stir.
- Tilt lid to allow steam to escape.
- After 5 hrs add spices and sugar, remove the lid and turn the heat up to high and cook down the butter for another hour or so.