Heat a large skillet to medium high heat. Add about a teaspoon of oil to the pan and make sure the oil spreads out to the ends of the pan.
Place one tortilla down on the heated pan. Add your slices of brie. Top with the fresh spinach. Place your other tortilla on the top and cover for about 3 minutes. Remove the cover and flip quesadilla over. Heat that side for another 3 minutes.
Remove quesadilla from the frying pan and slice into four triangles.