Preheat oven to 400 degrees Fahrenheit. Line a baking sheet with foil. Spray one side of a tortilla with non-stick cooking spray and place that side down on baking sheet. Sprinkle about ¼ cup cheese on tortilla, then place ½ cup cooked chicken, ½ tbsp cilantro, 3 to 4 slices of apple, 2 to 3 tbsp salsa, and remaining ¼ cup shredded cheese. Spray another side of a tortilla with cooking spray and place that side up onto of the already prepared side. Press down slightly. Continue process with remaining two tortillas.
Place in oven and bake about 5 minutes. Remove from oven and press down slightly again. Carefully flip the tortilla over and cook another 5 minutes until golden and cheese on the interior is melted.
Transfer the quesadillas from baking sheet to a cutting board. Cut into triangles as if you were cutting a pie and serve immediately with a side of any extra salsa.