Preheat the grill and keep the lid shut.

Butterfly the whole chicken (photos in this easy garlic herb roast chicken)-start by placing it standing on your cutting board with the cavity down. Then using a sharp knife run it across the sides of the back bone and remove it entirely.

Then place the chicken on the board with the cut side down and using the palm of your hand and the knife, smash the breast of the chicken to gently crack the bone and flatten the whole chicken.

Take a small paring knife and make a small slit in the breast bone and the thigh bone junction. In a wide shallow bowl or baking plate prepare the marinade by mixing the balsamic, garlic, mustard, rosemary and olive oil. Whisk well and season with salt and pepper.

Coat the chicken in the marinade making sure to go between the skin and flesh. It’s best if chicken marinades for at least half an hour.

Place the chicken on the grill (back side down) and close the bbq lid for 15 minutes.

Flip the chicken (breast side down) and close the bbq lid for another 15 minutes.

Then flip the chicken one last time and close the lid on the bbq for an extra 10-15 minutes (depending on the size of your chicken).

An instant meat thermometer should read 180 degrees in the thighs/drumstick part and 170 degrees for the breast.

Remove the chicken from the grill and tent lightly with foil for about 5 minutes before cutting through to make sure it stays juicy.