Set the oven to 350°F (175°C) and lightly coat a 9x13-inch baking dish with nonstick spray or a thin layer of oil.
In a large mixing bowl, stir together the pulled chicken, taco seasoning, drained tomatoes with green chilies, and sour cream until thoroughly incorporated.
Begin assembling the casserole by spreading half of the tortilla chips (or torn tortillas) evenly across the base of the prepared dish.
Spoon half of the chicken mixture over the chip layer and spread evenly. Scatter one cup of the shredded cheese across the top.
Repeat the layering process with the remaining chips, the rest of the chicken mixture, and finish with the final layer of cheese.
Place the casserole in the oven and bake uncovered for 25 to 30 minutes, or until the cheese has melted completely and the dish is bubbling at the edges.
After baking, garnish with your preferred toppings such as chopped herbs, jalapeños, or avocado slices. Serve immediately, optionally paired with rice or a fresh salad.