Preheat the oven to 350°F. Generously spray a 9×13-inch baking dish with nonstick cooking spray. Set it aside.
Crush the bag of Doritos, and pour all but 1½ cups into the bottom of the prepared baking dish.
Using a medium-sized mixing bowl, whisk together the cream of chicken soup, cream of mushroom soup, and sour cream until smooth.
In a large mixing bowl, combine the drained corn, salsa, shredded chicken breast, and 3 cups of shredded cheese. Add the soup and sour cream mixture and stir until well combined.
Evenly spread the cheesy chicken mixture over the top of the crushed chips.
Evenly spread the reserved 1½ cups of chips over the top of the chicken mixture.
Evenly sprinkle the reserved 1 cup of shredded cheese over the crushed chips layer.
Bake for 25 minutes. Serve while hot.