Preheat your oven to 350°F (175°C).

In a large skillet, heat a bit of cooking oil over medium heat. Add the diced chicken and cook until it's no longer pink in the center, about 5-7 minutes.

Add the diced bell peppers and onion to the skillet, cooking until they are slightly softened, about 3-4 minutes.

Sprinkle the fajita seasoning over the chicken mixture, stirring well to combine. Add a pinch of salt and pepper to taste.

Reduce the heat to low, then stir in the cream of chicken soup and sour cream, mixing until everything is well-coated and creamy.

Gently fold the corn into the mixture, allowing it to mix evenly throughout.

Pour the chicken mixture into a greased 9×13-inch baking dish and spread it out evenly.

Sprinkle the shredded cheese over the top of the casserole.

Place the dish in the preheated oven and bake for 25-30 minutes, or until the cheese is bubbling and slightly golden.

Remove from the oven and allow to cool slightly before serving.