Cook your chicken and cut into small cubes. Another great option is the cooked rotisserie chickens that you can find at your local grocery store. You can cut them into small cubes as well or shred. Set out your chicken, cheese and tortilla shells.
Warm your pan on medium-high heat and add a small amount of butter (you can also use cooking spray or olive oil). Gently lay tortilla shell in the pan and layer cheese and chicken on one half of the tortilla.
Fold the other half of the tortilla over the meat and cheese and press firmly. This will create the quesadilla.
Adjust your heat so that the cheese in your quesadilla will have time to melt without the tortilla shell getting burned. You will now want to flip the quesadilla over gently to cook the other side. Your melted cheese will hold it together, but still be careful and use a large spatula. Once both sides are browned, remove the quesadilla from the heat and cut into fourths with a pizza cutter or large knife. Garnish with your favorite toppings.