PREHEAT broiler. Spread large nonstick frying pan with cooking spray. Heat on medium heat. Add chicken and chili powder; cook and stir 2 min. Add corn and 2 Tbsp. of the salsa; cook and stir 3 min. or until chicken is cooked through and sauce is thickened.
SPRAY 4 of the tortillas with cooking spray. Place, sprayed side down, on large foil-covered baking sheet; sprinkle with half of the cheese. Top evenly with the chicken mixture and remaining cheese. Cover each with second tortilla; spray with cooking spray.
BROIL, 4 to 5-inches from heat, for 2 to 3 min. or until golden brown. Turn quesadillas over with large spatula; continue broiling 2 to 3 min. or until tortillas are golden brown and cheese is melted. Cut each into 4 wedges. Serve with the remaining salsa.