The primary ingredient in a quesadilla is cheese. Traditionally, a quesadilla consists of a tortilla, usually made from corn or flour, that is filled with cheese and then folded in half and warmed on a grill or skillet. The melting cheese is essential for the dish, giving it a rich flavor and gooey texture. While cheese is the main ingredient, quesadillas can also be filled with various other ingredients, including meats, vegetables, and spices, providing an array of flavors and customizations. Quesadillas are a staple of Mexican cuisine and are enjoyed both as a snack and a meal.