Prepare the night before if time allows: Heat a frying or griddle pan over high heat. Sear the cut sides of the lemon halves for about 5 minutes until nicely charred. Allow them to cool slightly, then squeeze the juice into a bowl.

Add the lemon zest, most of the thyme leaves, chopped garlic, and softened butter into the bowl. Use a fork or masher to combine thoroughly. This can be made a day in advance and kept chilled.

Scatter the chopped onions into a roasting tin. Place the turkey crown on top and season generously with salt and pepper. Let both the turkey and butter rest outside the fridge for about 1-2 hours before roasting.

Preheat the oven to 200°C (180°C fan, gas mark 6). Smear the flavored butter all over the turkey skin.

Place the roasting tin with the turkey in the oven. Roast for approximately 1 hour and 30 minutes, basting every 30 minutes until the turkey is golden and internal temperature reaches 70°C.

Once roasted, let the turkey crown rest for at least 20 minutes before carving. Remember to reserve onions and pan juices for gravy.

For added presentation, sear more lemon halves to serve alongside the turkey, garnishing with reserved thyme and some bay leaves.