PREHEAT oven to 400°F. Mix mustard and mayo in shallow bowl. Empty contents of seasoning packets into shaker bag or onto plate.
DIP chicken into mustard mixture, turning to evenly coat both sides. Shake 3 or 4 pieces at a time with the coating mix, then place in foil-lined 15x10x1-inch baking pan. Discard any remaining coating mix.
BAKE 15 minutes or until cooked through.