Heat grill to medium-high heat.
Grill vegetables 5 to 7 min. or until crisp-tender, turning after 4 min. Cool slightly.
Cut VELVEETA into 1/2-inch cubes; place in microwaveable bowl. Add milk.
Microwave on HIGH 1-1/2 to 2 min. or until VELVEETA is completely melted and sauce is well blended when stirred. Meanwhile, coarsely chop vegetables.
Spread tortilla chips onto microwaveable plate; top with vegetables and VELVEETA sauce.