Preheat your skillet or frying pan over medium heat.
In a small bowl, mix together the chili powder, cumin, garlic powder, salt, and pepper.
Rub the chicken breasts with the spice mixture, making sure to coat them evenly.
Heat the olive oil in the skillet and add the seasoned chicken breasts.
Cook the chicken for about 6-8 minutes on each side, or until it reaches an internal temperature of 165°F (75°C).
Once the chicken is cooked, remove it from the skillet and let it rest for a few minutes. Then, slice it into thin strips.
Wipe the skillet clean and return it to medium heat.
Place one tortilla in the skillet and sprinkle half of the shredded cheese evenly over the tortilla.
Arrange the sliced chicken on top of the cheese, and then sprinkle the remaining cheese over the chicken.
Top with another tortilla and press down gently.
Cook the quesadilla for about 2-3 minutes on each side, or until the tortillas are golden brown and the cheese is melted.
Remove the quesadilla from the skillet and let it cool for a minute before slicing it into wedges.
Repeat the process with the remaining tortillas and ingredients to make more quesadillas.