HEAT oven to 375ºF.
COOK and stir peppers and onions in skillet sprayed with cooking spray on medium heat 5 min. or until crisp-tender. Transfer to large bowl. Add chicken, 1/2 cup enchilada sauce and 3/4 cup VELVEETA; mix lightly.
POUR 1/2 cup of the remaining enchilada sauce into 13x9-inch baking dish sprayed with cooking spray. Spoon 1/4 cup chicken mixture down center of each tortilla, roll up. Place, seam-sides down, over sauce in dish; top with remaining sauce and VELVEETA. Cover.
BAKE 15 min. or until enchiladas are heated through and VELVEETA is melted.