HEAT oven to 375°F.
SPREAD cracker crumbs onto bottom of 9-inch square baking dish sprayed with cooking spray.
MICROWAVE milk, VELVEETA and cream cheese in large microwaveable bowl on HIGH 1-1/2 min. or until smooth, stirring after each minute. Whisk egg yolks and chives until well blended. Stir into VELVEETA mixture.
BEAT egg whites in small bowl with mixer on high speed until stiff peaks form; gently stir into VELVEETA mixture. Pour into prepared dish.
BAKE 20 to 25 min. or until puffed and golden. Serve immediately.