Spray a 13×9 dish with cooking spray. Preheat oven to 350 degrees.
In a large bowl, combine soup, sour cream, milk, chiles, onion, garlic, and pepper.
Line bottom of 13×9 with 6 tortillas. Sprinkle with 3 cups of chicken and pour 1/2 sauce over top and spread to cover. Sprinkle with 1/2 of the cheese. Repeat.
Bake for 30 – 40 minutes or until hot and bubbly. Let stand 10 – 15 minutes before serving.
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