In a medium bowl, combine the cooked chicken, cheddar cheese, Monterey Jack cheese, chili powder, cumin, garlic powder, onion powder, salt, and black pepper. Mix well to ensure the chicken is evenly coated with the spices and cheese.
Lay out the flour tortillas on a clean surface. Spread half of the chicken and cheese mixture evenly over one half of each tortilla.
Fold the other half of each tortilla over the filling to create a half-moon shape.
Heat a large skillet or griddle over medium heat. Add butter or oil to the skillet.
Carefully place one or two quesadillas in the hot skillet, being careful not to overcrowd the pan. Cook for 3-5 minutes per side, or until golden brown and the cheese is melted and gooey.
Remove the cooked quesadillas from the skillet and place them on a cutting board. Repeat with the remaining quesadillas, adding more butter or oil as needed.
Cut each quesadilla into wedges and serve immediately with your favorite toppings like salsa, sour cream, or guacamole.
Notes
For a spicier kick, add a pinch of cayenne pepper or some chopped jalapeños to the filling. You can also experiment with different cheese combinations like pepper jack or a Mexican blend.