Using Leftover Lamb in Shepherds Pie

A Proper Home for Sunday's Leftover Lamb

There is something deeply satisfying about a joint of lamb that keeps on giving. You carve it hot on Sunday with mint sauce and roast potatoes, then on Monday it returns as something altogether softer and more comforting: a shepherd's pie with a golden, fork-ridged mash and a filling that tastes as though it has been simmering for hours.

Worth getting the name right, because your butcher will appreciate it. Shepherd's pie is made with lamb — a shepherd looks after sheep, after all. Make the same dish with beef and it becomes a cottage pie. Ours is the lamb version, and it is arguably the best possible use of a roast that came out slightly bigger than the table could manage.

The aim is simple: a savoury, gravy-rich mince that clings together rather than swimming, and a mash sturdy enough to sit on top without sinking. Get those two things right and you have a midweek supper that feels like a celebration all over again.

Preparing the Leftover Lamb

Start with roughly 500g of cooked lamb, off the bone. Pull it apart with two forks or your fingertips into pieces about the size of a thumbnail. Resist the urge to blitz it in a processor — fine mince turns to paste, and the whole point of using leftovers is that you can taste the roast it came from.

As you go, set aside the good bits and discard the rest:

• Keep any jellied roasting juices, gravy or resting liquid from the tin — that is pure flavour and it belongs in the pan.
• Keep the crisp, well-browned edges of the joint, chopped small; they add little pockets of savoury depth.
• Discard hard knobs of fat, sinew and any dry, greyish slices that have gone leathery in the fridge.

If your lamb was served with a minted gravy, don't worry — a spoonful of that works beautifully in the filling too.

Building the Savoury Mince

Warm a good glug of oil or a tablespoon of dripping in a wide, heavy pan over a medium heat. Soften one large onion, finely chopped, with two carrots and a stick of celery diced small, for about ten minutes until sweet and glossy. Add two cloves of garlic, grated, and cook for another minute.

Stir in one tablespoon of plain flour and two teaspoons of tomato purée, and let them cook out for a minute or two — this is what thickens the filling and stops it turning soupy. Now add 300ml of stock (lamb if you have it, chicken if you don't), a generous tablespoon of Worcestershire sauce, a teaspoon of dried thyme or a few sprigs of fresh, and a bay leaf if one is within reach. Let it bubble gently for five minutes until it coats the back of a spoon.

Fold in the shredded lamb, along with any reserved gravy or jellied juices, and simmer for ten minutes more. Season carefully — leftovers are already salty, so taste before you reach for the salt cellar. Finish with plenty of black pepper. The filling should be thick, glossy and just loose enough to spoon.

The Mash That Holds It All Together

For the topping, use 900g of floury potatoes — Maris Piper, King Edward or similar. Peel, cut into even chunks and boil in salted water for fifteen to twenty minutes until a knife slides in without resistance. Drain thoroughly, then return the pan to the heat for a minute to drive off excess steam. This single step is the difference between fluffy mash and wallpaper paste.

Mash or rice the potatoes, then beat in 75g of butter and up to 100ml of warm milk — warm, not cold, or the mash turns gluey. An egg yolk stirred through gives a lovely set and a deeper golden crust. Season generously with salt and white pepper.

Assembling and Baking

Heat the oven to 200C, 180C fan, gas mark 6. Tip the lamb filling into a 1.5-litre ovenproof dish and level it. Spoon the mash over the top in blobs, then spread it gently with the back of a spoon or a fork — dragging the tines across the surface to leave ridges and peaks. Those ridges are where the crisp, browned edges happen, so don't smooth them away.

A scattering of grated mature cheddar is optional but excellent. Bake for 25 to 30 minutes until the top is deeply golden and the filling bubbles up around the edges. If the mash is colouring too quickly, cover loosely with foil. Let it stand for ten minutes before serving — the filling firms as it rests, which makes it far easier to portion neatly. Something sharp and green alongside, buttered peas or braised cabbage, cuts through the richness.

Making It Ahead, Freezing and Reheating

This is a dish that rewards planning. Assemble it completely, cool it quickly, then chill for up to two days. Add ten minutes to the baking time if it goes into the oven fridge-cold, and cover with foil for the first half so the top doesn't catch.

• To freeze: freeze the assembled, unbaked pie in a foil-lined dish, well wrapped, for up to three months.
• To cook from frozen: bake covered at 180C for about an hour, then uncovered for 20 to 25 minutes to crisp the top.
• To reheat portions: cover and warm in the oven at 180C until piping hot throughout, or microwave individual portions and finish under a hot grill for a minute or two to revive the crust.

Cool any leftovers within two hours, keep them covered in the fridge for up to two days, and reheat only once. Done properly, a Sunday roast can feed you three times over — and the third meal might just be the best of the lot.