Add all ingredients except heavy cream to slow cooker.
Cover and cook on low 6-8 hours or on high 3-4 hours.
Purée the soup with an immersion blender if you have one. Or, purée soup in 3-4 batches in a regular blender. Return soup to the slow cooker.
Stir in heavy cream and serve immediately.
Note: Perfect to pair with grilled cheese sandwiches.