Preheat the oven to 375°F (190°C).
In a large bowl, combine the shredded chicken, taco seasoning mix, salsa, sour cream, black beans, corn, and half of the chopped green onions and cilantro. Mix well until evenly combined.
Spray a 9×13-inch casserole dish with cooking spray.
Layer half of the tortilla strips evenly in the bottom of the casserole dish.
Spread half of the chicken mixture over the tortilla layer.
Sprinkle half of the shredded cheddar and Monterey Jack cheeses over the chicken mixture.
Repeat the layers with the remaining tortilla strips, chicken mixture, and cheeses.
Cover the casserole dish tightly with aluminum foil and refrigerate for up to 24 hours if making ahead.
When ready to bake, remove the casserole from the refrigerator and let it sit at room temperature for 15 minutes.
Bake covered with foil for 25 minutes.
Remove the foil and bake for an additional 10 minutes, or until the cheese is melted and bubbly.
Garnish with the remaining green onions and cilantro before serving.