Slow-Roast Easter Stuffed Lamb

Step 1: Preheat the oven to 180°C/350°F (160°C fan-forced). Roast the hazelnuts for 8 minutes. Let them cool, then roughly chop.

Step 2: Blitz the mushrooms in a food processor, scraping down the sides as needed, until they are chopped into pieces about 3 mm/0.1 inch wide.

Step 3: Melt the butter in a non-stick pan over high heat. Add the eschalots, garlic and mushrooms. Cook, stirring regularly, for 5 minutes or until most of the liquid released by the mushrooms has evaporated. Add the spinach and cook until wilted.

Step 4: Transfer the filling to a bowl and let it cool for 20 minutes. Stir in the remaining stuffing ingredients.

Step 5: Pile the stuffing onto a piece of cling wrap and use your hands to shape it into a log about 35 cm/13.5 inches long. Wrap it tightly in the cling wrap. Freeze for 3 hours, or up to 3 days, until firm.

Step 6: Place the lamb shoulder fat-side down. Cover it with plastic wrap or baking paper. Use a rolling pin or meat mallet to pound the meat into a rectangle about 40 x 22 cm (15.5 x 8.5 inches), aiming for an even thickness of about 1.75 cm (2/3 inch). Trim and reposition pieces as needed to form the rectangle.

Step 7: Sprinkle the lamb with half the salt and pepper. Unwrap the frozen stuffing log, place it on the lamb and roll the lamb tightly around it, finishing with the seam side down.

Step 8: Tie the roll securely with kitchen twine at 2 cm/0.8-inch intervals.

Step 9: Preheat the oven to 220°C/425°F (200°C fan-forced).

Step 10: Rub the lamb roll all over with the olive oil, then sprinkle it with the remaining salt and pepper.

Step 11: Toss the potatoes with the salt, pepper and olive oil in a large roasting pan, not a baking tray. Place the lamb on top of the potatoes, diagonally if needed to fit.

Step 12: Roast for 30 minutes to start browning the lamb and render some fat.

Step 13: Lower the oven temperature to 160°C/320°F (140°C fan). Cook for 2 1/2 hours, or until the internal temperature is 98°C/208°F or the meat can be fairly easily teased apart with two forks. Check in a discreet spot.

Step 14: Transfer the lamb and potatoes to a tray and loosely cover with foil while you make the gravy.

Step 15: Tilt the roasting pan and scoop off the fat, leaving 3 tablespoons behind. Keep the dark brown juices in the pan and discard the excess clear fat. If there is not enough fat, add butter.

Step 16: Put the pan directly on the stove over medium heat. Once the fat is hot, sprinkle in the flour and stir for 1 minute.

Step 17: Stir while slowly pouring in the stock. Add the soy sauce and keep stirring as the gravy bubbles gently and thickens to a maple syrup consistency.

Step 18: Taste and add salt and pepper if desired. Pour the gravy into a jug, straining it if needed.

Step 19: Remove the string from the lamb and slice it into pieces about 2 cm/0.8 inch thick.

Step 20: Arrange the lamb on a platter and surround it with the potatoes. Serve with gravy and, if desired, sprinkle with extra chopped pistachios. Serve with sautéed green beans if you like.