COOK chicken and vegetables in large nonstick skillet on medium heat 10 min. or until chicken is done and vegetables are crisp-tender, stirring occasionally. Remove from skillet. Carefully wipe skillet clean with paper towel.
SPOON 1/4 of the chicken mixture onto half of each tortilla. Top with VELVEETA; fold in half.
COOK, in batches, in skillet 2 min. on each side or until quesadillas are browned on both sides and VELVEETA is melted.