This dish works as well with a shoulder of lamb as it does with a leg. But they require slightly different methods. You’ll find both below.

Whichever cut you’re using, start this the night before by marinating the lamb. In a large stainless-steel bowl beat the yogurt with the tomato puree. Continue beating as you dribble in the olive oil and wine. Mix in the garlic, bay, thyme, salt and pepper. Make deep incisions all over the lamb and then put it in the marinade, rubbing the marinade all over the meat. Cover and turn occasionally.

For lamb shoulder The next day heat the oven to 180 Celsius. Take the lamb out of the marinade (keep any excess for later) and place in a roasting tin. Cover with parchment or foil and bake for two hours. Take the meat out of the oven, then pour the juices into the reserved marinade and keep for later. Remove the cover and put the meat directly on the oven rack, with the tin on the shelf beneath, to catch the dripping juices, and cook for another 45 minutes.

For leg of lamb Heat the oven to 225 Celsius. Place the lamb on a roasting tray (do not cover) and roast for 40 minutes. Then remove the meat from the tray and put it directly on the oven rack, turning it the other way around. Place the tray underneath, to catch the dripping juices, and cook for another 15 minutes.

Remove whichever lamb cut you’re using from the oven and allow to stand in a warm place for 20 minutes before carving.

In the meantime pour a cup of water into the roasting tray and put over a medium heat to clean the pan. Add this liquid to the reserved juices and marinade and reduce the lot in a small saucepan until you are happy with the flavour.

Carve the meat into thick slices and arrange on a serving platter on top of the aubergine bechamel, and pour the reduced roasting juices over.

For the aubergine bechamel

Roast the whole aubergines in a very hot oven until they are soft and charred all over.

When cooled, peel under running water and squeeze well, to get out as much liquid as you can. Mash the aubergines with a fork or in a food processor.

Next melt the butter in a medium saucepan, add the flour and a pinch of salt, and cook together for a minute, until the flour is pale and sandy. Then pour in the boiling milk, all at once, and whisk until the sauce is smooth and thick. Cook for a couple of minutes, stirring well.

Stir in the aubergine puree and allow to heat through, then stir in the cheese. When it has melted, taste and add more salt if needed.