I like to make things ahead and this is how I proceed in the morning, so it is ready to brown later:
Coat a non-stick frying pan with Pam or lightly brush with olive oil. Place one (1) flour tortilla in the frying pan, spread grated cheese, green onions, and fresh cilantro leaves on top. Sprinkle with a little red chili flakes to add zip, if you wish.
Place the second flour tortilla shell on top. Cover pan, put into the refrigerator. Remove frying pan with the tortillas about 30 minutes before browning to allow ingredients to come down to room temperature.
Place on the stove over medium heat and brown quesadilla, then flip and brown the other side. If cheese is not melted, turn heat down a little, and heat a few minutes longer. Remove from pan and let sit approximately 1 minute for cheese to set up a little.
Cut with a large, sharp knife into four wedges. Place on individual serving plates and serve with salsa if desired.
Cheese Quesadillas Recipe: https://whatscookingamerica.net/KarenCalanchini/QuesadilaCheese.htm