1. Spray large skillet with cooking spray; heat over medium heat. Add chicken and undrained tomatoes; cook 10 minutes or until chicken pieces are no longer pink in centers and liquid has evaporated, stirring frequently.
2. Spread chicken mixture evenly onto bottom half of each tortilla to within 1 inch of edge. Sprinkle 1/2 cup cheese over chicken mixture on each tortilla. Fold each tortilla in half to cover filling.
3. Clean skillet. Spray with additional cooking spray; heat over medium-high heat. Cook quesadillas 3 minutes on each side or until golden brown on both sides. Cut into wedges to serve.