Preheat the oven to 350°F. Grease a 2 ½-quart baking dish and set aside.

In a large skillet, heat the oil over medium heat. Sauté the onion and bell pepper until softened.

Add the cooked chicken, black beans, corn, diced tomatoes with green chilies, taco seasoning, and garlic salt. Cook for about 5 minutes, stirring occasionally.

Add up to ¼ cup of the reserved tomato liquid to achieve the desired texture.

Remove the skillet from heat and stir in the sour cream and ½ cup of the shredded cheese until well combined.

Spread the chicken mixture evenly in the prepared baking dish.

Sprinkle the crushed tortilla chips over the top, then layer on the remaining shredded cheese.

Bake in the preheated oven for 25-30 minutes, or until the cheese is melted and bubbly.

Serve garnished with chopped fresh cilantro or sliced green onion, if desired.