Oaxaca cheese is the cheese used when making quesadillas. It is named after Mexican state of Oaxaca which is famous for its very rich and amazing gastronomy.
This semi-soft cheese becomes soft and stringy when melted, it is less salty than your average cheese and it has a very mild flavor. And that is exactly what you need when making quesadillas, a cheese that gives you the texture but does not take over the flavor. Mozzarella is its European cousin.
Make some corn tortillas, fill with cheese and melt in a pan. Open and fill with a spoon of pico de gallo. Too delicious.