Coat an 11x8" (or similarly sized) baking dish with oil or butter. Set it aside for now.
Sauté the diced onion and bell pepper with the butter in a large saucepan. Cook until they are tender.
Add in the tomatoes with green chiles, diced green chiles, along with the seasonings. Stir well to combine.
Add in the cream cheese and let it begin melting. Then add in a cup of the cheddar cheese. Cook on low heat until melted.
Place you cooked chicken in your prepared baking pan. Pour the cheese sauce all over the top, and gently stir to coat it all. You could do this in a separate large bowl if you choose, but I don't see any need to dirty another dish. Spread the mixture even in the pan.
Sprinkle the remaining cheddar cheese over the top of the casserole.
Bake for 25-30 minutes or until it is bubbly and slightly golden around the edges.
Let it rest for 5-10 minutes before serving.
Enjoy!
Notes
If you would like to make this a little closer to the classic version, substitute 12 corn tortillas for the pasta. Cut the tortillas into 1 inch squares, or strips about 1/2 x 2 inches. Layer the tortilla pieces between layers of the chicken and sauce. Top with the cheese topping and bake as directed above.
You could make this recipe keto-friendly by substituting tapioca or arrowroot starch for the all-purpose flour when thickening the sauce. Then omit the pasta and use keto-friendly tortillas cut into pieces like mentioned above.