In a medium saucepan with 1 Tbsp. olive oil, sauté onion until soft. Stir in chilies, chicken and ½ cup sauce; set aside.
Meanwhile, evenly brush 1 side of 4 tortillas with ½ of the olive oil. Evenly top half of a tortilla with ¼ of the cheese, chicken filling and then the remaining cheese. Fold over tortilla to close.
Sauté 5 minutes, turning over once, or until cheese is melted. To serve, cut each quesadilla into 4 wedges. Serve with remaining sauce, heated.
Recipe Notes
Tip: Use ground beef instead of shredded cooked chicken.