In a small bowl, mix the cumin, chili powder, garlic powder, onion powder, salt, and pepper. Rub this spice mixture evenly over both sides of the chicken breasts.

Heat 1 tablespoon of olive oil in a skillet over medium heat. Add the seasoned chicken breasts and cook for 6-7 minutes on each side, until golden brown and cooked through (internal temperature should reach 165°F). Remove from heat and let rest for 5 minutes.

After the chicken has rested, slice it into thin strips or bite-sized pieces.

Place a large skillet or grill pan over medium heat. Warm each tortilla for about 1 minute on each side until soft and warm. Remove from the pan and set aside.

Place a tortilla back into the skillet. Sprinkle a generous amount of shredded cheese over the tortilla, then layer with sliced chicken, bell peppers, and onions (if using). Top with more cheese and place the second tortilla on top.

Cook the quesadilla for 2-3 minutes on each side, flipping carefully with a spatula, until the tortilla is golden brown and crispy, and the cheese is melted. If necessary, lower the heat to ensure the cheese melts properly without burning the tortilla.

Remove the quesadilla from the skillet, cut into wedges, and serve with sour cream and salsa on the side.