In a Dutch oven, cook bacon over medium heat until crisp. Remove to paper towels to drain; set aside. Saute celery and onion in the drippings until tender. Add garlic; cook 1 minute longer. Stir in the cauliflower, water, clam juice, bouillon, pepper and thyme. Bring to a boil. Reduce heat; simmer, uncovered, until cauliflower are tender, 15-20 minutes.

In a small bowl, combine xanthan gum and 1 cup cream until smooth. Gradually stir into soup. Bring to a boil; cook and stir until thickened, 1-2 minutes.

Stir in clams and remaining half-and-half; heat through (do not boil). Crumble the cooked bacon; sprinkle over each serving.