1. Bring 5 cups water to boiling in large saucepan.
2. Cut 6 broccoli flowerets in quarters. Cook in boiling water for about 4 minutes. Remove and reserve for garnish.
3. Cut the stems off remaining broccoli; peel with vegetable peeler. Coarsely chop broccoli and add to water in saucepan with onion, rice, milk, salt and pepper. Simmer for about 20 minutes or until vegetables are tender.
4. Working in batches, remove vegetables with some liquid to food processor or blender. Add cheese and mustard. Whirl until smooth, 2 to 3 minutes. Return to saucepan. Add more milk if desired. Gently reheat over low heat; do not let boil. Garnish with reserved broccoli.