Number of People
Whisk the buttermilk with the mustard, rosemary and garlic. Place the chicken in a large resealable plastic bag and pour in the buttermilk mixture. Place in the refrigerator to marinate for at least 4 hours or up to 24 hours.
Remove the chicken from the marinade and shake off any excess marinade; discard remaining marinade. Sprinkle the salt and pepper evenly over the chicken.
Turn the grill on. Select the program Poultry and press OK. Lightly grease the cooking plates with cooking spray. Once the purple indicator light has stopped flashing, place the chicken on the grill and close the lid.
Cook until the indicator light has changed to red.