Pour about ¾ cup enchilada sauce in the baking dish, and spread until the bottom of the dish is coated. Top with a layer of about 8 tortilla halves so that the entire dish is covered. Sprinkle evenly with about 1 cup black beans, ½ cup corn and a fourth of the green onions. Then sprinkle with a heaping cup of the chicken, and about ¾ cup shredded cheese. Repeat with a second layer of tortillas, then sauce, then beans, corn, green onions, chicken, and cheese. Then a final layer of tortillas, sauce, beans, corn, green onions, chicken and cheese. Then conclude with a final layer of tortillas and sauce (reserving about ¾ cup of cheese to add partway through baking). Cover the pan with aluminum foil, then bake for 20 minutes.