Preheat a skillet with oil on medium heat. Add in the chicken and taco seasoning. Cook for 4 minutes.
Add in the bell pepper and onion, cook for another 5 minutes or until chicken and veggies gain color and are cooked through. Set aside.
On a clean skillet, add a bit of butter or oil and place a tortilla on top. Add Mexican cheese and chicken mixture to one half of the tortilla. Top with more cheese. Fold the tortilla over to close.
Cook for a few minutes and once the tortilla is golden on one side, flip and cook for a few more minutes until the second side is golden brown. Make sure that the cheese has melted. Repeat with the rest of quesadillas.
Serve while the quesadillas are still warm!
