Clean and dice the nopales. Chop the onion and mince the garlic. In a skillet, cook the nopales, onion, and garlic over medium heat in their own juices for about 40 minutes. Once cooked and all the liquid has evaporated, set aside. If you buy pre-cleaned and diced nopales, prep time will be shorter.

Roast the guajillo chiles and tomatillos for about 50 minutes or until well charred. Toast the chile de árbol peppers on a gas grill. Once cooked, remove the husks from the tomatillos and stems from the chiles. Blend with 1 cup (240 ml) of water and 1 teaspoon of salt until smooth.

To assemble the quesadillas, heat a tortilla on a griddle or skillet over medium heat for 1 minute. Add the nopales and cheese to one half of the tortilla, fold it over, and cook for about 3 minutes per side until golden and crispy on both sides.

Cut each quesadilla into four pieces and serve with the salsa. Enjoy!