Preheat the oven. Set your oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish.

Warm the aromatics. Heat oil in a skillet over medium. Add the diced onion and bell pepper with a pinch of salt. Cook 4–5 minutes until softened and lightly golden.

Season the chicken. In a large bowl, combine the cooked chicken with taco seasoning. Add the sautéed onions and peppers.

Build the creamy base. Stir in the salsa, black beans, corn, and green chiles. Fold in the cream cheese (or sour cream/Greek yogurt) until evenly mixed. Taste and adjust salt and pepper. You’re aiming for a saucy, scoopable mixture.

Prep the tortillas. If using corn tortillas, stack and cut them into quarters (or tear into bite-size pieces). If using chips, lightly crush them so they layer easily but still have texture.

Layer the casserole. Spread a thin layer of the chicken mixture in the baking dish. Add a layer of tortillas or chips, then a generous handful of shredded cheese. Repeat layers until you’ve used everything, finishing with a thick blanket of cheese on top. Plan for 3–4 layers depending on your dish depth.

Bake. Cover with foil and bake for 15 minutes. Remove the foil and bake another 10–15 minutes, until the cheese is melted, bubbling, and lightly browned around the edges.

Rest and garnish. Let it rest 10 minutes so it sets and slices cleanly. Sprinkle with chopped cilantro. Add optional toppings like avocado, chopped tomatoes, jalapeños, and a squeeze of lime.

Serve. Scoop into bowls or slice into squares. Pair with a simple salad or rice if you want to stretch it further.