"Lasagne, I think, is the truest weekend food: the Saturday dinner, the Sunday lunch. You can make it in a rush on a weeknight, but it's not nearly as good, and scrambling to get it ready takes all the fun out of it. You want half a day to devote to it really," explains Ella Risbridger, author of new cookbook Midnight Chicken. "Lasagne can be party food, picnic food or leftovers, but most of all it is proper comfort food. Done well, it's both a joy to eat and a joy to cook."

"This version is vegetarian, which I prefer," she adds. "Both lighter and more grown-up than its meaty counterpart, it's also beautiful: The deep umber of sweet squash, green-and-gold slivers of charred leek to temper the sweet with the bitter, punchy green kale for vitamins and to cut the fat a little, all layered with rich, melty, nutmeg-y bechamel (or something like it, anyway) infused with Parmesan rind, peppercorns and a bay leaf."

Ingredients:

(Serves 6)

About 300g no-cook lasagna sheets, depending on the dimensions of your dish

1 x 125g ball of mozzarella

25g Parmesan

Freshly grated nutmeg

Black pepper

Salad or garlic bread, to serve

For the vegetable filling:

800g squash, such as butternut (but any is fine)

1 garlic bulb

Olive oil, for drizzling

50g butter

Small handful of thyme

2tbsp white wine

3 large leeks

400g kale

For the cheese sauce:

60g Parmesan

60g strong Cheddar

40g butter

40g plain flour

600ml milk

200ml double cream

6 black peppercorns

1 bay leaf

1 Parmesan rind

Salt

Method:

1. Pre-heat your oven to 180C.

2. First, make the filling. Peel your butternut squash – a big knife works much better than a standard peeler for this. Use a spoon to scrape out the seeds, then chop into dice. Tip the dice into a large roasting tin. Take your garlic bulb, and slice the top off to expose just the very tips of the cloves. Wrap in foil, like a parcel, leaving it slightly open at the top. Drizzle the tops of the garlic cloves with olive oil, then seal the parcel and tuck in the tin with the squash.

3. Cut half of the butter into tiny cubes and dot among the squash. Grind over some pepper, then strip the thyme leaves from their stalks and scatter them in, then pour over the white wine. Put in the oven to roast for 40 minutes or until the squash is good and caramel-y.

4. Meanwhile, turn your attention to the leeks. Split them lengthways and rinse thoroughly under the tap (leeks are great at hiding grit and mud). Chop roughly, then muddle with your hands to separate the leeks into their constituent layers. In a large frying pan over a medium-low heat, melt the remaining 25g butter and allow it to brown slightly. Give the leeks a last shake dry, and tip them in. Stir to coat in the brown butter, then leave them to lightly char (maybe 20 minutes), giving them a stir every so often – this adds a lovely rich bitterness to balance the sweetness of the squash.

5. Rinse the kale, and chop roughly with scissors. That's all you're going to do to the kale. Leave it be.

6. When your squash has been in the oven for about 20 minutes, check on it: It should be happily doing its thing. If it looks like it's burning, spoon over some of the juices from the bottom of the tin and loosely cover with foil, before returning it to the oven for the remaining 20 minutes.

7. Next up, the cheese sauce. Grate both the cheeses – you can mix them together; it's fine. (Give your leeks a stir.) Melt the butter in a saucepan over a medium-low heat, and when it's foaming, add the flour, stirring to form a golden-coloured paste (breathe in - it smells amazing). Cook your roux for a couple of minutes, stirring constantly, then remove from the heat. (Stir your leeks again – they should be softened and starting to catch by now.) Gently and slowly introduce the milk to your roux, stirring the whole time. You want to pour with one hand, and stir with the other, to avoid lumps. Keep pouring. Keep stirring - you can get any lumps out by stirring. When your sauce is smooth, stir in the cream. Add the peppercorns, bay leaf, Parmesan rind and a good grating of nutmeg. Bring up to a simmer, stirring constantly, then cook for about 10 minutes. Turn off the heat, and fish out the peppercorns, bay leaf and Parmesan rind. Add the grated cheese, stirring until the cheese has melted and the sauce is smooth. Taste – you might want salt.

8. Check your squash, which should be very soft with caramelised edges by now; your garlic too should be soft, like butter left out on a warm day. Remove, but leave the oven on. Squeeze the soft garlic into your cheese sauce and stir well to fully incorporate. Decant the squash into a bowl and take the leeks off the heat.

9. Dig out a tin or baking dish about 30cm x 20cm, and 5cm deep: It's time to assemble your lasagne. Squash in first, a thin layer; next, a handful of kale, then lasagne sheets in a single layer, followed by cheese sauce, then leeks and more kale. Another layer of squash, lasagne sheets, cheese sauce, leeks and kale; then a final of squash and lasagne sheets, followed by the end of the cheese sauce, spreading it right to the corners of the tin.Tear the mozzarella and scatter over the top, then grate over the last 25g of Parmesan, some nutmeg and a twist of black pepper.

10. Bake for 45 minutes or until the pasta is soft and the cheese is golden-brown and bubbling. Serve with a sharp side salad (or garlic bread) and cold white wine.