Many crock pot recipes actually call for frozen chicken. I am pretty sure the "fix it and forget it" recipe books for slow cookers specifically say to use the chicken while it is frozen. My favorite frozen chicken recipe is super easy. Just toss some frozen boneless, skinless chicken breasts in the crock pot. Pour 1 c teriayki sauce over the chicken and then pour a can of pineapple chunks over the top, juice and all. Cook 4-5 hours on high but check frequently as cooking times may vary. This is great alone or over rice.