Peel garlic cloves and finely chop. Combine chopped garlic and butter in a bowl and mix together.
Thaw the turkey if necessary. Remove the turkey from the bag and pat the skin dry with a paper towel. Place the turkey in a roasting rack pan with the breast facing up. Loosen the turkey skin by sliding your fingers between the skin and the breast. Start at the cavity and work your way towards the neck. Spread the garlic butter mixture with your fingers under the skin on the breast meat. Coat the skin of the turkey with olive oil and season with cracked black pepper and a pinch of sea salt.
Peel onion and cut into quarters. Chop carrots into 3cm lengths. Place onion and carrot inside the cavity of the turkey. You can also substitute the onion and carrot for your favourite stuffing.
Truss the turkey by using butcher’s twine to or a food safe cooking string to tie the turkey’s legs together.
Preheat conventional oven to 225°C. Place the turkey in the oven and cook for 30 minutes. Turk the oven down to 175°C and cook for a further 2.5-3 hours. Cooking times may vary depending on your oven, however we recommend using a meat thermometer to check that the turkey has reached at least 76°C in the thickest part of the leg. Set turkey aside for 20 minutes to rest before carving.