Preheat oven to 375°F. Grease 13×9-inch baking dish.
Heat oil in a large skillet. Add chicken; cook, stirring occasionally, until no longer pink.
- Stir in bell peppers, onion, chiles and seasoning mix. Reduce heat to low; cook, stirring occasionally, until vegetables are slightly tender.
Spread 1/2 cup taco sauce onto bottom of prepared baking dish. Cover with 5 tortillas.
- Spread with half of chicken mixture and another 1/2 cup taco sauce. Sprinkle with 1 cup cheese. Repeat with remaining ingredients.
Bake for 15 to 20 minutes or until heated through and cheese is melted.