In a Dutch oven, combine the cauliflower, carrot, celery, water and bouillon. Bring to a boil. Reduce heat; cover and simmer for 12-15 minutes or until vegetables are tender (do not drain)., In a large saucepan, melt butter. Stir in the flour, salt and pepper until smooth. Gradually add milk. Bring to a boil over medium heat; cook and stir for 2 minutes or until thickened. Reduce heat. Stir in the cheese until melted, adding hot pepper sauce if desired. Stir into the cauliflower mixture.