PLACE potatoes on microwaveable plate. Prick in several places. Microwave on HIGH 9 to 10 min. or until tender, turning over and rearranging every 3 min. Let stand 5 min. Cut potatoes lengthwise in half; scoop out centres, leaving 1/8-inch-thick shells.
MASH potatoes in medium bowl. Stir in dressing, milk, broccoli and bacon; spoon into shells. Microwave 2 to 3 min. or until heated through.
SPOON Cheez Whiz into microwaveable bowl. Microwave 30 sec. or until melted; stir. Spoon over potatoes.