In a resealable plastic bag, or flat container with lid, mix dressing and mustard.
Add chicken and marinade for 6 hours (or overnight if you have time)
Before you turn on your grill, spray it with pam.
Heat your grill so it’s nice and hot.
Place marinated chicken breasts on grill meaty side down to get a great grill mark- then turn it about 15 degrees to get a nice bar-b-que cross grill mark
Grill over hot grill 10 minutes on each side or until chicken is no longer pink (cook until internal temp reads 160)
Remove from grill and let rest 15 minutes
Notes
This marinade really zings on grill, but chicken can also be baked in 350 degree oven until chicken is done.