Chicken Enchilada Casserole

Name: Chicken Enchilada Casserole
Prep time: 20 min
Cook time: 30 min
Total time: 50 min
Cuisine: American, Mexican, Latin American, TexMex
Ingredients: 1 tablespoon olive oil; 1 medium white onion, peeled and diced; 1 large red bell pepper, cored and diced; 1 (4 ounce) can diced green chiles; 2 (15 ounce) cans beans, rinsed and drained (I used one can pinto, one can black beans); 1 (8 ounce) can whole kernel corn, drained; 3 cups (about 1.5 pounds) shredded or diced cooked chicken; 3 cups red enchilada sauce, homemade or store-bought, divided; 12 corn tortillas, halved; 3 cups shredded Monterrey Jack or Mexican blend cheese; toppings: chopped fresh cilantro, diced red onion, thinly-sliced green onion and/or diced avocado