Preheat the oven to 375 degrees and prepare an 8x8-inch baking dish with cooking spray and set aside. Cook the ground chicken in a skillet over medium heat until fully cooked and no pink remains.
Add the taco seasoning and onion to the skillet. Stir to combine. Cook for 3 minutes until the onions soften and become fragrant.
Add the black beans, salsa, diced tomatoes and green chiles to the skillet. Then stir until well combined.
Stir in the Greek yogurt.
Fold in the white corn tortilla pieces until well combined and fully coated in the mixture.
Add 1/2 cup of cheese to the skillet and stir to combine.
Scrape the mixture into the prepared baking dish and gently spread it into an even layer.
Sprinkle the remaining 1 cup of cheese on top of the casserole.
Sprinkle 3/4 of the crushed Doritos on top of the casserole, and reserve the remaining amount. Place the casserole into the oven and bake for 15 minutes until the sides are bubbling and the top is browned. Sprinkle the remaining Doritos on top of the casserole and return to the oven for 5 minutes.
Allow 10 minutes to cool and then serve warm with your choice of toppings.