Set oven control to broil. Spray 13x9-inch broiler-safe (not glass) baking dish with cooking spray.
In medium microwavable bowl, mix chicken, 1/2 cup of the salsa, 1/2 cup of the cheese, the salt and pepper. Microwave uncovered on High 2 minutes or until thoroughly heated. Spoon about 1/3 cup chicken mixture down center of each tortilla; roll up. Place, seam side down, in baking dish. Pour remaining 1 cup salsa over enchiladas; sprinkle with remaining 1/2 cup cheese.
Broil with top about 6 inches from heat 8 minutes or until cheese is melted. Serve immediately.