In a large saucepan, saute onion and garlic in oil until tender. Add the broth, carrots, potatoes, salt, thyme, pepper and bay leaf. Bring to a boil. Reduce heat; cover and simmer for 20-30 minutes or until vegetables are very tender.
Remove from the heat; cool slightly. Discard bay leaf. In a blender, puree carrot mixture in batches. Return to the pan. Stir in half-and-half; heat through (do not boil).