Preheat oven to 425°F | 220°C for standard ovens, or 390°F | 200°C for fan forced. Lower the oven shelf to the lowest part of your oven.
Combine the herb butter ingredients in a bowl and mix well. Reserve half of the herb butter in the refrigerator for later.
Line a large roasting pan with foil or parchment paper. Arrange the 4 halves of garlic cut-side down on the bottom of the pan with 4 sprigs each of thyme and rosemary, half of the olive oil and 1 slice of lemon.
Thoroughly pat the turkey dry with paper towels. Stuff with the remaining heads of garlic halves, lemon slice, a squeeze of lemon from the remaining slice, herbs and a drizzle of olive oil.
Melt the butter and rub it all over the turkey, including under the skin. Season generously all over with salt and pepper. Place the turkey on top of the garlic and herbs in the pan BREAST-SIDE DOWN. Drizzle with the remaining oil.
Roast uncovered for 30 minutes for a small turkey under 13 pounds (6 1/2 kg), or 45 minutes for a larger turkey over 14 pounds (7 kg plus).
Turn the turkey over (breast-side up) with a pair of tongs, a clean tea towel or oven mitts (heat-proof gloves) and baste with pan juices.
Spread half of the reserved herb butter over the top of your turkey with a spoon or brush (be careful, the turkey will be hot and the butter will melt nicely over the skin). Pour any remaining juices over your turkey.
Reduce heat to 325°F |165°C (for standard ovens), or 300°F | 150°C (fan-forced). Roast, uncovered, for an hour.
Slather turkey generously with remaining butter and roast for 30 minutes. Baste again, then continue roasting for a further 30 minutes or so, depending on the size of your bird. *Tent loosely with foil if starting to brown too fast.*
(For an extra large turkey, you may need an additional half hour to an hour.)
For extra crispy skin, broil (or grill) in the last 5-10 minutes, keeping your eye on it so it doesn't burn, until the skin is crispy and golden browned all over.
Tent turkey with foil and allow it to rest for 20-30 minutes before carving and serving.
Remove 2 1/2 cups of the liquid from the pan juices (top up with stock if you need to), strain and reserve for your gravy.
Recipe courtesy of Cafe Delights