Preheat oven to 350 degrees. Spray 9x13" pan with cooking spray and set aside.
Crush the bag of Doritos and cover the bottom of the dish
Set aside 1 cup of shredded cheese. Mix together the remaining cup and all other ingredients in a large bowl. Pour chicken mixture over Doritos
Bake uncovered apprx 20 minutes. Top casserole with remaining 1 cup of cheese and bake an additional 5-10 minutes until cheese is melted