How to Make It
Stir together all ingredients in a 6-quart slow cooker. Cover and cook on LOW until pears and cranberries are very soft, about 4 hours. Transfer mixture, in batches, to a blender. Remove center piece of blender lid (to allow steam to escape); secure lid on blender, and place a clean towel over opening in lid to avoid splatters. Process until smooth, about 1 minute. Transfer to a bowl. After processing all cranberry mixture, return to slow cooker.
Increase heat to HIGH, and cook, uncovered, stirring occasionally with a wooden spoon, until mixture has thickened, 2 1⁄2 to 3 hours. Spoon mixture into 16 (4-ounce) jars, and let cool to room temperature, about 2 hours. Cover with jar lids, and chill 8 hours or up to 2 weeks.