Put the cashews into 300ml of water and soak for 30 minutes.

Preheat the oven to 180°C/350°F/gas mark 4.

Peel the celeriac and slice it into long strips like sheets of lasagne – about ½cm thick. Mix with 1 tablespoon of oil and a pinch of salt, then lay on two baking trays. Scrub the sweet potato, skin on, and slice into bite-size pieces. Toss with 1 tablespoon of oil and a pinch of salt so the pieces are fully coated, and lay on third baking tray.

Bake the celeriac and the sweet potatoes for 25 minutes, or until soft. Take them out of the oven, but leave it on. Peel and roughly chop the onion and garlic. Chop the chilli finely, removing the seeds if you prefer less heat. Finely slice the mushrooms and the courgette. Chop the sun-dried tomatoes very finely.

Put 2 tablespoons of oil into a large family-size pot over a high heat. Add the onion, garlic and chilli and fry for 4 minutes, stirring regularly until the garlic is golden and the onions are transparent. Add the mushrooms, courgettes and bay leaf and continue to fry for 5 minutes, stirring regularly. Add the wine and reduce for 2 minutes. Then add the chopped tomatoes, sun-dried tomatoes, tomato purée, honey/agave syrup, salt and pepper.

Once the sweet potatoes are cooked, add them to the tomato sauce. Bring to the boil, then allow to simmer on a reduced heat for 20 minutes, stirring occasionally.

To make the cashew cream, drain and rinse the soaked cashews. Whiz in a blender with the other cashew cream ingredients (including the basil stalks) until really smooth.

Cover the base of a large family-size baking dish with half the cashew cream. Over this lay half the baked celeriac, then pour over all the tomato sauce. Make another layer with the rest of the celeriac and finish with the remaining cashew cream. Bake for 15 minutes, until the cashew cream sets and the lasagne has a nice baked appearance.