Serves 8 with leftovers, takes 5 hours
At this time of year lamb is very much in it’s prime. This roast lamb recipe makes a spectacular Sunday lunch, but it’s also simple enough to prepare on your lunch break and serve up as a (rather indulgent) weeknight dinner – excellent for when you’re entertaining guests.
Boulangère potatoes are very similar to pommes dauphinoise, however they’re cooked in stock rather than cream. We go one better, cooking a beautiful lamb shoulder on top to slowly confit the potatoes in it’s drippings.
You can find the recipe, plus plenty of other superb one pot meals, in our newest cookbook. Perfect for yourself or as a gift.
Ginger Pig One Pot: First published in 2025 by Mitchell Beazley, an imprint of Octopus Publishing Group Ltd
Photography copyright ©️ Sam A Harris 2025
A good hour before you start cooking, remove the lamb from the fridge and allow it to come up to room temperature. Preheat the oven to 150ºC (300°F), Gas Mark 2. Slice the unpeeled potatoes and the onions as thinly as you can – a mandoline makes this easier. Thinly slice 6 cloves of the garlic. Lightly grease a roasting tin big enough to take all the vegetables with the lamb on top. Arrange the potatoes, onions and sliced garlic in layers in the roasting tin, adding the thyme leaves and plenty of salt and pepper as you go. Make sure the vegetables are fairly even (but it doesn’t need to be perfect). Pour over the stock.
Season the lamb well all over and cut the remaining 6 cloves of garlic into wedges. Use a sharp knife to make incisions all over the lamb. Push the garlic pieces into the meat and then break up the rosemary into small sprigs and push these into the incisions, too. Place the lamb on top of the layered potatoes and place the tin into the oven. Roast the lamb for 4 hours, basting a couple of times with the fat that collects in the tin. If the potatoes or onions around the edges seems to be browning too fast, cover with foil.
Take the lamb out of the tin and place it on a carving dish, then wrap it in foil and cover in a couple of tea towels to rest without getting cold or drying out.
If there is a lot of liquid in the tin and you’d like to brown the potatoes a bit more, spoon off the liquid into a jug. (It will be a mixture of fat and juices, so let it separate and pour off the fat. This breaks the one-pot rule, but if the lamb has released a lot of delicious liquid, you could simmer it with a pinch of flour and some seasoning, then strain it and serve as a gravy.) Turn the oven up to 180ºC (350°F), Gas Mark 4, and cook the potatoes for up to 25 minutes, checking every 5 minutes or so, until golden and done to your liking.
When the potatoes have crisped up and the lamb has rested for at least 15 minutes, serve the meat in thick slices, alongside the meltingly soft potatoes.
3kg (6lb 8oz) bone-in shoulder of lamb
1.6kg (3lb 8oz) waxy potatoes, scrubbed
2 onions
12 cloves of garlic, peeled
oil or butter, for greasing
leaves from 2 bushy sprigs of thyme
1 litre (1¾ pints) vegetable or lamb stock
2 sprigs of rosemary
salt and freshly ground black pepper
