Remove the neck and giblets from the cavity of the turkey (if desired, save to make gravy). Dry the skin of the turkey with paper towel. Fold the wings under the turkey.
Roughly chop ½ of one of the onions. Remove the leaves from 4 sprigs of rosemary. Add the chopped onion and rosemary leaves to a food processor along with the butter, bacon, garlic cloves, salt and pepper. Blitz into a paste.
Stuff the paste under the skin of the turkey’s thighs and breast. Lightly coat the turkey all over with olive oil. Season with salt and pepper.
Prepare the barbecue for indirect cooking over medium heat (190°C to 230°C). If using a Weber Q barbecue, set up your barbecue with a convection tray and a trivet.
Chop the remaining onion into quarters. Place the onion quarters and the two remaining sprigs of rosemary into the cavity of the turkey. Using butchers string, tie the legs together.
Roast the turkey over indirect medium heat for the required cooking time or until the internal temperature has reached 71°C. The internal temperature will continue to rise 3°C to 6°C while resting (final doneness temperature for turkey is 74°C). To calculate the cooking time for turkey, allow for 20 minutes, plus an additional 20 minutes per kilo. For example, for a 5kg turkey allow 20 minutes plus 5 x 20 minutes for a total of 120 minutes.
Once the turkey has cooked, leave to rest for 20 minutes before carving.
The maximum sizes for the Weber Q’s: Weber Baby Q 1000: turkey roll only, Weber Baby Q1200: 3kg, Weber Q2000: 3kg, Weber Q2200: 4kg, Weber Family Q3100: 4.5kg, Weber Family Q3200: 6kg.