PREP: Heat broiler. CLEAN: Wash hands. Spray foil-lined baking sheet with nonstick cooking spray. Place pounded chicken on baking sheet. CLEAN: Wash hands. In small bowl, blend remaining ingredients.

COOK: Broil chicken 5 minutes 4 to 6 inches from heat. Turn chicken over and spread evenly with sour cream mixture. Broil about 2 minutes more or until topping is puffed and lightly browned and internal juices of chicken run clear. (Or insert instant-read meat thermometer in thickest part of chicken. Temperature should read 170 degrees F.)

SERVE: Serve with green beans, sliced French bread and lemon tart, if desired.

CHILL: Refrigerate leftovers immediately.