In a 6-quart slow cooker combine all of the ingredients. Cover and cook on high about 2 hours or until pears are tender. Use an immersion blender to puree mixture until smooth. (Or transfer, in batches, to a food processor or blender. Cover and puree until smooth.)
Cook, uncovered, on high about 6 hours more or until very thick, stirring occasionally. Cover and chill overnight.
Ladle into half-pint canning jars or freezer containers, leaving a 1/2-inch headspace. Seal and label. Store in the refrigerator up to 3 weeks or freeze up to 1 year.