Are they boneless or if they aren't, are you willing to debone them?
This one is winner in my house:
Grilled Chicken Paillard
4 whole chicken breasts (deboned and trimmed)
marinade:
½ cup Dijon mustard
½ cup dark brown sugar
¼ cup soy sauce
¼ cup bourbon
2 tsp. Worcestershire sauce
basting sauce:
½ cup apricot preserves
¼ cup white vinegar
4 ½ tsp. Worcestershire sauce
1 Tbl. Dijon mustard
1 Tbl. Honey
½ tsp crushed red pepper
Garnish:
Toasted sesame seeds
Place chicken breasts one at a time into a Ziplock bag, removing as much air as possible before sealing. Pound to ¼ inch thickness using a rolling pin.
In a bowl, combine marinade ingredients, mixing with a whisk until smooth. Transfer to a 1 gallon Ziplock bag and add the chicken breasts. Seal the bag and agitate the contents until all of the breasts are covered. Refrigerate for 2 3 hours, turning every so often to ensure that all of the breasts are coated.
Combine sauce ingredients in a food processor to chop up any apricot pieces. Transfer to a saucepan and simmer for 15 minutes for the flavors to mingle.
Grill or broil the breasts. Cook for 2 minutes and turn over. Baste with the sauce and cook an additional 2 more minutes or more. Baste frequently. Chicken is done when it feels resilient to the touch.
Transfer to plate and sprinkle with sesame seeds if desired. Serve immediately.