In a small bowl, mix together the chili powder, ground cumin, onion powder, garlic powder, and kosher salt.
Take the sliced chicken breasts and sprinkle the spice mixture over them. Toss until the chicken is evenly coated. Allow it to marinate for at least 15 minutes.
In a large skillet, heat 1 tablespoon of olive oil over medium heat. Add the sliced onion and a couple of pinches of kosher salt. Sauté until the onions become translucent, about 3-4 minutes. Add the sliced bell peppers and continue to cook for another 5 minutes until they are tender. Remove the vegetables from the skillet and set them aside.
In the same skillet, add the remaining tablespoon of olive oil. Once hot, add the marinated chicken strips. Cook for about 6-8 minutes or until the chicken is fully cooked and no longer pink. Return the sautéed vegetables to the skillet and mix everything together.
On a large tortilla, sprinkle a generous layer of shredded Monterey Jack cheese. Add a portion of the chicken and veggie mixture on one half of the tortilla, then fold the other half over.
In the same skillet, cook the folded quesadilla for 2-3 minutes on each side, or until golden brown and crispy. Repeat with the remaining tortillas and filling.
Slice the quesadillas into wedges and serve warm with your favorite toppings like salsa, guacamole, or sour cream.
