I buy a lot of the the boneless, skinless chicken breasts that come frozen an a package from Costco or Sam's club. I have found that if you put the frozen breast on the grill, over indirect heat, and cooked slowly that the meat is very tender and moist. I season the meat about halfway through cooking with salt, pepper and a little garlic powder. Right before removing from the grill I add some bar b que or grilling sauce. cook it in and it has lots of flavor, and is very satisfying.