PULL off any outer green leaves from the head of cauliflower. Cut off the protruding stem end close to the head, making it even with the bottom of the head of cauliflower. Cut a 1/2-inch deep "X" in the base of the cauliflower. Place cauliflower, flower side down, and water in large microwavable bowl; cover with vented plastic wrap. Microwave on HIGH 10 min. or until tender. Remove and let stand, covered, 5 min.

MEANWHILE, whisk together dressing and flour until well blended. Gradually add milk, whisking until well blended. Microwave 3-4 min. or until thickened, stirring after 2 min. Add shredded cheese; stir until melted.

PLACE cauliflower in shallow casserole dish. Pour sauce over cauliflower. Mix Parmesan and bread crumbs together; sprinkle over cauliflower. Broil for 2-3 min. or until topping is lightly browned.