How to Make It
Heat olive oil in a large skillet over medium-high. Add onion and garlic; sauté 3 minutes or until tender.
Combine onion mixture, broth, and next 5 ingredients in a 4-quart slow cooker. Cover and cook on HIGH for 7 hours.
Stir half-and-half into soup. Process soup, in batches, in a blender until smooth, stopping to scrape down sides as necessary. Pour soup into bowls. Garnish, if desired.