Preheat the oven to 425 degrees F.
Heat the oil in a large skillet over medium high heat. Sauté the mushrooms until they are lightly browned, about 5 minutes.
Assemble the quesadillas on a parchment paper-lined sheet pan.
Sprinkle half a tortilla with cheese. Spoon on the mushroom mixture and sprinkle with additional cheese. Fold over the tortilla and bake for 10-12 minutes.