Leek, Mushroom and Kale Lasagne

Some of the ingredients in this dish can be a bit divisive - kale, mushrooms, blue cheese - but you're going to have to trust me when I say that this dish is absolutely delicious and so much more than the sum of all its parts.

A lasagne is a thing of pure, comforting joy and I'm always in the mood for it whether it be the traditional number with tomatoes and mince or something a little more adventurous like this one. Using the best of the produce at this time of year together with a little garlic and a punchy cheese sauce, I guarantee you will be going back for more!

Leek, Mushroom and Kale Lasagne

Serves 8

200g kale or cavolo nero, shredded, tough stalks removed 
2 leeks, washed, trimmed and cut into 1cm rounds 

2 small knobs of butter 

2 tbsp oil 

400g mushrooms, sliced 

2 garlic cloves, finely chopped 

1 tsp dried Italian herbs

250g fresh lasagne sheets 

3 tbsp coarse fresh breadcrumbs

sea salt and freshly ground black pepper

For the white sauce 

800ml milk

4 bay leaves 

1 onion, sliced 

3 celery sticks, chopped

A few black peppercorns 

75g unsalted butter 

75g plain flour 

75g blue cheese

1 tbsp dijon mustard

Heat the oven to 180°C/160°C fan/gas 4. For the white sauce, heat the milk in a heavy-based pan with the bay leaves, sliced onion, celery and peppercorns. When the mixture reaches a simmer, remove the pan from the heat and leave to infuse. 

Bring a large pan of salted water to the boil and add the kale and the leeks. Cook for 3-4 minutes or until the leeks are just tender. Drain well, then set aside. 

Heat a knob of butter and 1 tbsp olive oil in a large frying pan over a high heat. Add half the mushrooms and season with salt and pepper. Fry, stirring often, for 5-10 minutes, making sure the liquid released by the mushrooms has evaporated and they have a bit of colour. Stir in half the garlic and half the thyme, cook for a minute more, then transfer to a plate. Repeat for the remaining mushrooms, thyme and garlic. 

Heat the butter for the white sauce in a medium heavy-based pan. Scatter over the flour and, using a wooden spoon, work it into the butter. Cook gently, stirring, for 1 minute. Set a sieve over the pan and pour in half the infused milk (discard the flavourings). Work this into the butter and flour mixture. As it thickens, pour in the remaining milk, then switch to a whisk and whisk the sauce until thick and smooth. Add half the blue cheese, the mustard and salt and pepper to taste. 

Mix a third of the white sauce into the kale and leeks, then taste and season with salt and pepper. Arrange one third of the kale and leeks over the base of a large deep baking dish (30cm x 24cm). Lay over a third of the pasta. Arrange another third of the greens over the pasta, followed by half the fried mushrooms. Pour over half the remaining white sauce and a another third of the lasagne sheets. Spoon over the last of the greens, then top with the rest of the mushrooms. Put the remaining lasagne sheets on top, then pour over the rest of the white sauce and smooth the top with the back of a spoon. 

Combine the remaining cheese and the breadcrumbs, then scatter this over the top of the lasagne. Drizzle with a little olive oil, then bake for 40 minutes, spinning round half way through the cooking time to ensure it's evenly browned.

TIP: Assemble up to a day ahead and keep covered in the fridge. Cook from chilled, adding another 5-10 minutes to heat through. Leftovers will keep in the fridge for up to 2 days. Reheat in a medium oven to serve.