Place the turkey on a cutting board and pat it dry all over with kitchen paper. Turn it breast side down, with the legs facing you and find the backbone – it’s the ridge right down the middle. Take your shears cut all the way through to the other side, starting at the end nearest you.

Turn the turkey around and repeat this step on the other side to remove the backbone – but be sure to keep it, it’ll make the most fantastic stock or gravy!

Turn the turkey over so the breast side is facing up, and spread the thighs and legs out. Place the palms of your hands at the base of the breast and press down hard – imagine you’re giving the turkey CPR!

You’ll feel a ‘snap’ as the breastbone breaks – this is what you’re after! – and the turkey will flatten out a bit more. Turn the legs over so that they are facing outwards and tuck the wingtips underneath.

Make sure the turkey is dry – if not, pat it with kitchen paper. Sprinkle with the salt on both sides and place in the fridge, uncovered, for six hours or overnight – this helps the skin to crisp up while roasting.

Spread the onions, celery and carrots (if using) on a large roasting tray and place a wire rack on top or position the turkey directly over the vegetables using large onions sliced in half as a sort of trivet.

Loosen the turkey skin over the breast and push flavored butter underneath. Spread the remaining butter over the whole turkey.

Place in the oven and cook until an instant meat thermometer (or temperature probe) registers 150°F / 65°C in the thickest part of the breast (this your pull temperature).

Remove the turkey from the oven and let it rest, loosely covered with foil, for at least 30 minutes. The temperature will continue to rise as the turkey rests to the recommended safe temperature of 165°F / 74°C. Check the temperature at the thickest part of the thigh – dark meat can be cooked until it reaches 175°C / 80°C.