Heat up a large pan over medium heat, and melt enough butter to thinly coat the bottom of the pan. Add the tortilla, and layer on the rest of the ingredients on one half of the tortilla round.
Cook for 5 minutes, until the bottom of the tortilla turns golden brown and the cheese inside has melted. Flip the unlayered half of the tortilla onto the other side and press together. Remove the quesadilla from the pan and slice into triangles. Enjoy!