Preheat oven to 400°F (204°C). Spray a 9X13 inch baking dish with nonstick cooking spray.
In a large skillet, over medium heat, add oil (1 tablespoon) and cook onion (1 large) until translucent. Stir in shredded chicken (1 rotisserie), taco seasoning (2 packages), diced tomatoes (1 can), diced chilies (1 can), sour cream (1 cup), and cream of mushroom soup (1 can) and heat through.
Place one-third of the crushed Doritos in the bottom of the baking dish then add half of the chicken mixture. Top with one-third of the crushed Doritos, then the remaining chicken mixture. Add the last third of the remaining Doritos and sprinkle the top evenly with cheese.
Bake, uncovered in the preheated oven until heated through and the cheese is bubbly about 20 minutes.
Notes
Chiles –Want to make sure your Mexican chicken casserole with Doritos isn’t too spicy? Don’t be turned off by the addition of green chiles in this recipe — while “green chiles” is a general term for peppers that include jalapenos, the canned chiles you buy at the store tend to be the milder cousin known as Anaheim peppers.
Cheese – This recipe calls for two — yes, two! — types of cheese. Cheddar is more potent and punchy while jack cheese (also known as Monterey Jack) is milder and melts faster. You’ll get a well-rounded cheese flavor with this pair!