1Mix broccoli, cauliflower and onion in very large (4-quart) bowl.
2Mix mayonnaise, cheese, sugar, salt and basil in small bowl. Add mayonnaise mixture to vegetables; toss gently to coat. Cover and refrigerate at least 2 hours or overnight.
3Just before serving, add bacon, lettuce, croutons and water chestnuts; toss lightly. Store covered in refrigerator.