To spatchcock the chicken place on a board breast side down. Using sharp scissor or poultry shears, cut along the length of the back bone. Open out the bird as much as possible and turn breast side up. Press down firmly to break the breast-bone and flatten the chicken.
Lift the skin from the breast of the chicken. Take care not to to tear the skin as you do so. Spread the garlic and herb butter over the the breast under the skin.
Thread 2 skewers diagonally through the bird to hold it flat. Grill breast side up for 25 minutes over medium hot coals.
Turn the chicken over and cook breast side down roast for 20 minutes. Turn back over and check to see if the chicken is cooked (see notes) and continue cooking if required.
It is important to check the chicken is fully cooked. The meats juices should run clear when pierced with a knife. If there are any traces of pink to the juices cook for longer.The best way to check is with a thermometer. The minimum temperature at the centre of thickest part of the bird should be 75℃/165°F.Nutrition information is approximate and is meant as a guideline only. (It does not include seasoning with salt and pepper.)