Put a pan on the stove over medium heat and put half of the butter on it.
To assemble the quesadillas place a tortilla on a plate, and put 1/4 of the melting cheese on it along with 1/4 of the chicken fajitas. Spread on the tortilla and then place another tortilla on top.
Put the quesadilla on the pan and let it cook for the cheese to melt for 2 minutes on every side for it to slightly turn golden brown.
Repeat the same process to make the rest of the quesadillas. Once ready, eat it along with some guacamole or spicy sauce.