Combine chicken and half the salsa in a medium bowl.
Place 4 tortillas on work bench. Top each with 1/2 cup chicken mixture and 1/3 cup cheese, then top with remaining tortillas.
Spray a medium frying pan with oil. Heat over medium heat. Place 1 quesadilla in pan and press down firmly. Cook for 2 minutes or until golden. Spray top of quesadilla with oil, then carefully turn over and cook for a further 2 minutes or until golden. Carefully transfer to a plate and cover to keep warm. Repeat with oil and remaining quesadillas.
Quarter quesadillas and sprinkle with coriander. Serve with sauce and remaining salsa.