Combine all ingredients EXCEPT half & half in the slow cooker. Cook on low for 8 - 10 hours or high for 4 - 6 hours. Blend about half the soup using an immersion blender (or just scoop it into your upright blender then return to slow cooker). Add half and half or heavy cream and continue cooking, uncovered, for about another 15 minutes, until heated through. Salt and pepper to taste. Serve and enjoy!