This Apple, Caramelized Onion, and Spinach Quesadilla is a delicious and unique twist on the classic quesadilla. The combination of sweet caramelized onions, tart apples, and fresh spinach creates a flavorful and satisfying filling. The quesadilla is then grilled until crispy and golden, making it the perfect appetizer or light meal. Serve it with a side of salsa or sour cream for dipping, and enjoy the delightful blend of flavors in every bite.