Whisk together the Italian dressing, lemon zest, sugar and salt. Pour the marinade into a gallon-sized, zippered bag.
Place four frozen chicken breasts into the bag with the marinade, seal the bag, and allow the chicken to thaw in the marinade overnight.
Or, if using fresh chicken breasts, pound them to a uniform thickness. Place them in the marinade and refrigerate for four hours.
Preheat the George Foreman Smokeless Grill to 425 degrees.
Place the chicken breasts on the grill and close the grill.
Grill the chicken for 5 minutes. Check the temperature. The chicken is done when it reaches at least 165 degrees F.
Assemble the sandwiches - bottom half of bun, slice of Cheddar, bacon, grilled chicken breast, lettuce, tomato, Ranch dressing, top half of bun. Enjoy!