Preheat the oven to 180C/160C fan/gas 4.
In a small bowl, mix together the olive oil, salt and pepper.
Pat the turkey crown dry with paper towels and then rub the olive oil mixture all across its skin, making sure to cover it all.
Stuff the cavity with the lemon slices and rosemary sprigs and transfer the whole crown to a roasting pan with a built-in rack.
Roast the turkey for about 20-25 minutes per pound (450 g). Because ovens vary, use a meat thermometer to check the internal temperature at the turkey’s thickest point. It’s fully cooked when it reaches 75°C (165°F).
Once cooked, let it rest, lightly covered with tinfoil, for about 15 minutes before carving.
In the meantime, make the cranberry sauce by combining the cranberries, orange juice, water, sweetener and orange zest in a small saucepan.
Bring the mixture to the boil, stirring occasionally. Once it’s bubbling, reduce the heat to low and let it simmer for about 15 minutes until the sauce has thickened considerably.
Taste a little to ensure it’s the right level of sweetness for your tastes (add a little more honey, maple syrup or sweetener if it’s too tart).
Serve the turkey slices drizzled with cranberry sauce, garnished with some optional rosemary sprigs.
