This recipe comes from Elise of Simplyrecipes: This version of a quesadilla pie is a casserole made in a pie dish with stacked flour tortillas and layers of cheesy filling, baked until browned and crispy. The beauty of quesadilla pie is that it's a great way to use up leftovers and odds and ends. The essentials are the tortillas and the cheese; after that it's up to you as to the variety and type of filling you want. Black beans are good, as are onions, chicken, tomatoes, mushrooms, or summer squash. All can be layered in with the cheese. Add as much chile as you want for heat and flavor.