Coat one side of each tortilla with cooking spray. Place sprayed sides down on cutting board or parchment paper. Sprinkle 1/4 cup of the cheese over half of each tortilla. Top with chili peppers and barbecued chicken. Fold tortillas in half, pressing gently.
Heat a 10-inch nonstick skillet over medium heat. Cook quesadillas, two at a time, in hot skillet for 4 to 6 minutes or until light brown, turning once. Remove quesadillas from skillet; place on a baking sheet. Keep warm in a 300 degree F oven. Repeat with remaining quesadillas. To serve, cut each quesadilla into 3 wedges. Serve with salsa, sour cream, and green onions. Makes 4 main-dish servings.