Make the marinade. Whisk all the ingredients together in a small bowl; set aside.
Pound the chicken thin. Working with 1 chicken breast at a time, place a breast inside a gallon zip-lock bag. Use a meat mallet, rolling pin, saucepan, or skillet to slightly flatten the breast to an even thickness from end to end. It should be around ¼ to ½-inch thickness.
Marinate the chicken. Place the chicken in the zip-lock bag with the marinade, massage to coat. Seal the bag and place in the bowl to prevent leakage. Refrigerate at least 4 hours or overnight. In this recipe, I marinated the chicken overnight. Do not marinate for more than 24 hours!
Prepare the grill (indoor or outdoor). Preheat the grill on high for 10-15 minutes, then scrape any debris from the grill grates and oil well.Or if you use a grill pan, set over medium-high heat.
Grill. Remove the chicken breasts from marinade and place the chicken breast on the prepared grill. Brush the chicken all over with the honey butter and grill. Flip the chicken breast at halfway point. Cook the chicken about 3 minutes each side or until the meat is registered at 165°F before removing from the grill. Do not overcook!
Rest the chicken. Transfer the cooked chicken to a platter, let rest 5 minutes before serving.