Combine all ingredients in slow cooker and cook on high for 4 hours.
Transfer contents of slow cooker to a blender or food processor. You can also leave the ingredients in the crock and use an immersion blender. Process the soup until smooth.
Ladle hot soup into bowls. Add a teaspoon of half and half to the top of the soup and swirl it with a knife. Top with a sprig of fresh parsley.