I grew up making quesadillas, the benefit of having a Hispanic mother who is a great cook. "Queso" is cheese in Spanish. And a quesadilla is a toasted tortilla with melted cheese inside. But in addition to cheese, you can put practically anything in a quesadilla. My favorites are mushrooms, olives, tomatoes, and onions. I don't cook these ingredients first, but it really is a matter of taste. You could if you wanted to.