First, make the herb butter by mixing the butter, chives, parsley, lemon zest, paprika, onion powder, garlic powder, thyme, rosemary, oregano, Cajun seasoning and salt and pepper together in a bowl or food processor until smooth.
Place the chicken breast side down on a chopping board. Use kitchen scissors to cut along both sides of the backbone and remove it. Turn the chicken over and press firmly on the breast to flatten it.
Rub the herb butter all over the chicken, both on and under the skin. Make sure the herb butter is evenly distributed.
Leave the chicken to marinate in the refrigerator for at least one hour to allow the flavours to infuse.
Preheat the barbecue to a medium heat 175 degrees Celsius / 347 Fahrenheit.
Place the chicken, skin side up, on the grill.
Cook slowly for 45 minutes or until the chicken has reached the right internal temperature. The chicken will be nice and tender at 75–80 Celsius / 167-176 Fahrenheit so keep a close eye on it.
Serve the chicken warm from the barbecue with potato wedges and a fresh salad, if desired. Enjoy!