Cook bacon in a large nonstick skillet over medium heat until crisp. Remove bacon from pan; crumble. Add onion and garlic to drippings in pan; sauté 3 minutes. Transfer onion mixture to a 4-quart electric slow cooker. Stir in broth and next 7 ingredients (through tomatoes). Cover and cook on LOW for 8 hours.
Stir in half-and-half and sherry. Ladle soup into bowls; sprinkle with crumbled bacon.