Pre-heat oven 190°C/170°C fan/Gas Mark 5.

Remove the leaves from the rosemary sprigs and chop finely. Combine the rosemary with the butter, finely chopped garlic cloves, salt and pepper.

Make around 20 small incisions in the skin of the lamb and rub over the rosemary and garlic mixture. Place the lamb into the roasting tin herb-side up with the whole garlic bulb alongside.

Roast for 1 hour 40 minutes to 2 hours, basting 2 or 3 times during cooking. Time will depend on the size of joint and how well-done you like it cooked.

Remove the lamb onto a warmed dish, cover with foil and rest for 25-30 minutes before carving.

To make the gravy, skim away and discard any unwanted fat from the cooking juices. Remove the roasted garlic and squeeze the pulp from the skin into a saucepan. Combine the skimmed cooking juices with the flour and mix to a paste. Whisk in the stock with the mint sauce and bring to a simmer, stirring until thickened. Adjust the seasoning to taste.

Slice the rested lamb thickly and serve with the gravy and some extra mint sauce served separately.

Cook's Notes

To make your own mint sauce, combine 3 tablespoons of freshly chopped mint with 4 tablespoons of white balsamic vinegar and season with some salt.

If darker gravy is preferred, add a few drops of liquid gravy browning when adding the stock.