Set out the cheese and steam heat the tortillas. Coat the bottom of a 13x9-inch baking dish with a little sauce. Roll 1/4 cup of the cheese into each tortilla and fit into the pan. Ladle 2 cups of the sauce over top, sprinkle with remaining cheese and bake at 425 degrees F until bubbly and browned. Sprinkle with chopped onion and cilantro to taste and serve.
Cheeses to use - such as Chihuahua (queso menonita), asaderos, or quesadilla, a good substitute can be Sonoma Jack, Others - Monterey Jack or mild cheddar.