Lamb Boulangere

Tasty and succulent dish for those drab autumn days when you're in need of some comfort food. From Lucas Hollweg of the Sunday Times.

1. 1

   Heat the oven to 200C/400F/Gas Mark 6. Arrange two oven racks one above the other. The lower one needs enough space to fit a roasting tin, the upper one enough for your leg of lamb.
   
   With the tip of a sharp knife, make about 20 cuts in the skin side of the lamb. Season well on all sides. Finely chop the herb leaves and mix into the butter with the crushed garlic. Using your hands, smear the butter all over the skin of the lamb and the meaty end of the joint, working it into the crevices and cuts. Put to one side while you get on with the potatoes.
   
   Use a knob of butter to grease a roasting tin that’s large enough to fit under your leg of lamb. Melt another knob of butter in a saucepan, then add the onions and a pinch of salt. Stir together, cover and cook for 5-10 minutes, until the onions have softened. You don’t want them to brown, just wilt.
   
   Use either a mandolin or the slicing blade of a food processor to slice the potatoes thinly. Layer the potatoes and onions in the buttered roasting tin, sprinkling each layer with thyme leaves and seasoning well. Start and finish with potatoes. You’ll probably only need one other layer of potato in between. Pour over enough stock to come just below the surface of the potatoes. Press the potatoes into place and throw the bay leaves on top.
   
   Put the potatoes on the lower shelf of the oven and position the lamb on the rack above. Cook at 200C/400F/Gas Mark 6 for 20 minutes, then turn down the heat to 180C/ 350F/Gas Mark 4 and cook for 1 hour 15 minutes to 1 hour 40 minutes, depending on how well done you want it. If the potatoes look like burning before the lamb is done, cover them loosely with a sheet of foil. When the lamb is cooked, remove it from the oven and allow to rest for at least 20 minutes.
   
   You may want to tip off a bit of the excess fat from the potatoes. If for any reason they aren’t brown, turn the oven back up to 200C/400F/Gas Mark 6 and leave them in while the lamb is resting, otherwise, switch the oven off and leave them in to keep warm. Serve the lamb on top of potatoes