Step 1

Heat the oven to 170C/fan 150/gas In a buttered roasting tin layer up the potatoes, onions, garlic, thyme and some seasoning, repeating until you’ve used all of the ingredients, ending on a final layer of potatoes. Pour in the chicken stock.

Step 2

In a bowl, mash the soft butter and the anchovy fillets and season with black pepper and a little salt. Rub this all over the lamb.

Step 3

Put the potatoes on the middle shelf of your oven and on the rack above put the lamb shoulder, ensuring that it’s directly above the potatoes, to catch all of its juices.

Step 4

Cook for 3-4 hours until the top of the potatoes are crisp and the lamb is tender. Cover the potatoes loosely with pierced foil if they start to get too dark – the juices will be able to run through the holes.