Preheat the oven to 350 degrees F. Lightly grease a 9X13-inch pan with cooking spray. Set aside.
Whisk together the enchilada sauce and salsa verde.
Toss the chicken with the garlic powder, onion powder, oregano, chili powder, cumin, salt and pepper.
Spread 1/3 of the sauce in the bottom of the prepared pan. Layer eight tortilla halves across the sauce (see pictures in the post for a visual). Sprinkle 1/3 of the cheese over the tortillas followed by 1/2 of the chicken. Drizzle with 1/3 of the sauce.
Layer another eight tortilla halves, 1/3 of the cheese, last 1/2 of the chicken, another 8-9 tortilla halves, remaining 1/3 cheese and remaining sauce.
Cover with greased foil and bake for 35-40 minutes. Uncover and bake another 10-15 minutes until bubbly and cooked through. Sprinkle with chopped cilantro. Let rest for 10-15 minutes (it will set up and be less runny as it rests) before serving.
Sauce: you can use all enchilada sauce if you want (omit the salsa verde and increase the amount of green enchilada sauce by 10-12 ounces).Make Ahead: the casserole can be assembled and refrigerated for up to 8 hours (the tortillas will soften more than if baked right away).