Tarragon Chicken and Leeks

4 skinless boneless chicken breast halves (about 1 pound)
1 cup sliced leeks (about 2 medium)
3/4 cup evaporated skim milk
1 TBS Dijon mustard
1 1/2 tsp chopped fresh tarragon or 1/2 tsp dried tarragon leaves
1 tsp cornstarch

Spray 10-inch skillet with nonstick cooking spray. Cook chicken breast halves in skillet over medium heat 12 to 14 minutes, turning once until juices run clear. Remove chicken from skillet; keep warm.

Cook leeks in skillet about 3 minutes, stirring frequently, until crisp-tender. Mix remaining ingredients, stir into leeks. Heat to boiling, stirring occasionally. Boil and stir 1 minute until slightly thickened. Add chicken; heat through.