1. Mist slow cooker with cooking spray. Mix ketchup, mustard and 1/3 cup cranberry sauce in a bowl. Cover remaining cranberry sauce; refrigerate.
2. Mix remaining ingredients and cranberry mixture in a bowl. Form into a loaf; transfer to slow cooker. Cover. Cook on low until a thermometer inserted into center registers 180ºF, 6 to 8 hours.
3. Preheat broiler. Transfer loaf to a foil-lined baking sheet. Brush with reserved cranberry sauce. Broil until sauce bubbles, 30 seconds to 1 minute. Let rest for 10 minutes before serving.