Preheat the oven to 400˚F.

Clean and pat dry the chicken. Season with salt and pepper. Place on a baking sheet and cook in the oven for 30 – 40 minutes until cook through. Remove from oven and let them rest for at least 20 minutes or until cool enough to handle. Remove and discard the skins. Shred the chicken with two forks into thin strips or bite-size pieces. Transfer to a small bowl and set aside.

Reduce the oven heat to 200˚F. Place a clean baking sheet in the oven.

On a work surface, lay out the tortillas. Working on the bottom halves of the tortillas, sprinkle half of the cheese. Add chicken, chilies, onion, and cilantro. Drizzle about 1½ tablespoon BBQ sauce over each tortilla. Sprinkle rest of the cheese. Fold the uncovered tortilla over the fillings to form a half-moon shape.

Heat a large flat griddle pan or 2 large pans over medium-high heat. Place 2 quesadillas on the griddle or 1 quesadilla on each large pan. Cook until crisp & golden brown on both sides, about 5 – 7 minutes total. Transfer the quesadillas to the baking sheet in the oven and keep warm. Repeat with the remaining quesadilla.

Transfer the cooked quesadillas to a clean chopping board. Cut each quesadilla into 4 wedges. Place the wedges on serving plates. Serve with guacamole, sour cream, and salsa.