Start by placing the chicken breasts in a large freezer bag. Using a meat pounder, gently pound the chicken to an even thickness.
Whisk together the Chick-fil-a sauce, olive oil, Worcestershire sauce, white vinegar, lemon juice, onion powder, garlic powder, and a generous pinch of salt and black pepper.
Pour the marinade over the chicken. Seal the bag tightly and give it a gentle shake.
Store the bag in the fridge for 4 to 24 hours, flipping occasionally.
Remove the chicken from the marinade and discard the marinade.
Preheat your grill or cast iron grill pan to medium-high heat. Place the chicken on the grill.
Cook until the chicken reaches an internal temperature of 165ºF, about 6 to 8 minutes per side.
Remove the chicken from the grill and let it rest for a few minutes before slicing.
Slice and serve warm.