Preheat the oven to 350 degrees Fahrenheit. Spray a 9 x 13 x 2-inch inch baking dish with nonstick cooking spray.
Add ½ cup of the enchilada sauce evenly to the bottom of the baking dish and layer 4 of the corn tortillas on top of the sauce.
Add half of the black beans, half of the corn, and half of the olives evenly over the tortillas.
Top with half of the chicken and 1 cup of the Colby Jack cheese. Repeat the layers starting with the enchilada sauce.
Add the remaining tortillas on top of the cheese, followed by another ½ cup of enchilada sauce and the last cup of Colby Jack cheese.
Cover the baking dish tightly with aluminum foil and bake for 20-25 minutes or until heated through. Remove the foil and bake for an additional 5 minutes or so to brown the cheese.
Let the casserole sit for about 5 minutes before serving the the toppings of your choice.