Mix oil, chili powder, cilantro, and salt together in a medium bowl. Add uncooked chicken, and toss to coat with seasonings.
Spray a 12″ skillet with cooking spray, and heat over medium-high heat. Add chicken, and cook approximately 5 minutes on the first side. Flip chicken breast over and cook for another 5 minutes.
Spread about 1/4 c. salsa on top of each piece of chicken. Arrange avocado slices evenly over salsa. Lay a layer of cheese on top of avocado. (You may need to cut the cheese slices into shapes that will fit on top of the chicken.
Cover the skillet, and cook for 5 minutes longer, or until cheese is melted. Serve and graciously accept compliments.
If you prefer, you can make this dish in the oven. Bake the chicken at 350 degrees F for 15-20 minutes until cooked through. Carefully remove and add toppings, and return to oven for 5-7 minutes until cheese is melted.
These cook times are approximate and work for thinly sliced chicken breasts. Please be sure your chicken is cooked completely before serving.