Heat a skillet over medium heat and add a small amount of olive oil or cooking spray.
Add diced onions and bell peppers to the skillet and sauté until softened, about 3-4 minutes.
Add the cooked, shredded chicken to the skillet and season with chili powder, cumin, salt, and pepper. Stir well to combine and cook for an additional 2-3 minutes.
Place a flour tortilla on a clean surface and sprinkle a layer of shredded cheese on one half of the tortilla.
Spoon a portion of the chicken mixture on top of the cheese layer.
Fold the tortilla in half to cover the filling, creating a half-moon shape.
Repeat the process with the remaining tortillas and filling.
Heat a separate skillet over medium heat and lightly coat with cooking spray or oil.
Place the filled tortillas in the skillet and cook for 2-3 minutes on each side, or until golden brown and crispy, and the cheese is melted.
Remove from the skillet and let cool for a minute before slicing into wedges.
Serve hot with your favorite toppings such as salsa, sour cream, guacamole, or chopped cilantro.