Harissa lamb, squash & chickpea lasagne

Preheat the oven to 230ºC, gas mark 8. Scrub the squash (no need to peel), halve and deseed it, then slice into 1cm crescents. Spread onto a large baking sheet. Sprinkle over the spices, then drizzle with 3 tbsp oil. Mix so everything is glossy, then arrange into a single layer. If cramped or overlapping, use 2 trays. Roast for 30-35 minutes, until soft, blistering and beginning to char. Remove and season generously with sea salt flakes.

Meanwhile, make the ragù. Add 1 tbsp oil to a large, heavy-based saucepan over a high heat. Once hot, add the lamb mince, season generously with salt, and cook for 10 minutes or so, until the liquid cooks away and the meat is browning.

Stir the baharat seasoning into the lamb, sizzle for 1 minute, then push the meat into a pile on one side. Reduce the heat to medium, add the remaining oil into the gap in the pan, then add the onion. Finely chop the coriander stems and add them with a generous pinch of salt. Sauté for 3 minutes to soften, stirring the onions occasionally (but not the meat).

Combine the onions and meat, add the chickpeas, chopped tomatoes and a tomato can of water, the harissa and honey. Simmer for 30 minutes until most of the liquid has cooked away, but the ragù is loose enough to flow when the pot is shaken. Remove from the heat. Finely chop the coriander leaves and stir in with the mint. Season to taste.

While the ragù simmers, make the white sauce by melting the butter in a medium-sized saucepan over a moderate heat. Add the flour to make a roux and stir for about 2 minutes until slack. Add about 100ml milk and stir into the roux until incorporated. Repeat 3-4 times, then gradually increase the amount of milk, using a whisk to ensure it’s smooth.

Add a scattering of finely grated nutmeg, the white pepper, a generous pinch of salt and 40g parmesan. Cook gently over a low heat for 10 minutes, stirring frequently, until the sauce thickens and there’s no lumps of raw flour.

To assemble the lasagne, spread 2 scant ladles of lamb ragù over the base of a large rectangular ovenproof dish, about 20x30x8cm (about 4.5L). Top with a layer of lasagne sheets. Arrange half the squash over them and top with just under one third of the white sauce. Top with more lasagne sheets, then half the remaining ragù. Add another layer of pasta, then the remaining squash and slightly less than half the remaining white sauce. Add more lasagne, the remaining ragù and a final layer of pasta, topped by the remaining white sauce. Scatter the remaining parmesan over the top.

Preheat the oven to 200ºC, gas mark 6. Bake for 50-60 minutes, until bubbling and golden on top and piping hot throughout (cover with foil if it starts to brown too quickly). Leave to cool for 10 minutes before serving for easier cutting and portioning.