Combine cauliflower, broth, celery, onion, salt and pepper in Crockpot™ slow cooker.
Cover; cook on LOW 7 to 8 hours or on HIGH 3 to 4 hours.
Pour cauliflower mixture into food processor or blender; process until smooth.
Add milk and Worcestershire sauce; process until blended.
Pour soup back into slow cooker.
Cover; cook on HIGH 15 to 20 minutes or until heated through.
