5 lbs Italian prune plums, pitted and halved
2 cups light brown sugar
1 large cinnamon stick (optional)
Place the plums, sugar and cinnamon stick in an oval, six-quart slow cooker. Cook on low 12-18 hrs, leaving the lid slightly askew for the second half of the cooking time. Cook until a thick paste forms with little to no visible "liquid". Use an immersion blender to process until smooth. Prep your jars/lids. Pour the butter in the jars, leaving 1/4 inch headspace. Process in a boiling water bath for 10 minutes.
Yield: about 1 pint "Elite" Ball jar, one 8-oz jar and 1 4-oz jar
Note: A great source for canning information is the Blue Book guide to preserving. I highly recommend it for learning how to can. Here are some of my other favorite canning books and supplies.