Preheat the oven to 200°C/180°C Fan.

Dry-fry the mushrooms in a large, shallow cast-iron frying pan over a medium heat for 6-7 minutes until softened. Remove from the pan and set aside.

In the same pan, heat 3 tablespoons of olive oil and add the carrots, celery and onions with a pinch of salt. Give the mixture a good stir so that the veggies are coated, then sweat for 15 minutes, stirring occasionally, until the ingredients are beginning to soften and have shrunk significantly. Add a splash more oil or water to loosen, if it starts to catch.

Add the tomato puree, sundried tomatoes, garlic, herbs, and chilli flakes and cook for 1 minute. Stir the mushrooms back in and cook for another minute until combined.

Tip in the chopped tomatoes, swill the can ¼ with water and tip that in too, and veg stock and mix through. At this point, add a pinch of salt and the sugar letting it dissolve in the liquid of the stew. Bubble for 6-7 minutes before stirring in the black beans with their bean stock, simmer for a further 5 minutes to let the beans soak up the flavours. You don’t want it to be too thick at this stage as it needs enough liquid to let the pasta cook and it will thicken in the oven. The ragu can be made the day before before adding in the pasta and baking!

Snap the lasagne sheets in half into the pan, pushing them down so they're submerged into the sauce. Cover with a lid and bake in the oven for 25 mins.

Remove the pan from the oven and stir in half of the parmesan. Check the pasta is fully cooked through - if it needs a little more time, add a splash more water or stock and bake for another 5-7 minutes.

Tear over mozzarella and scatter with the remaining parmesan. Return to the oven for around 5-6 minutes or until the cheese is melted and everything is bubbling.

Let the lasagne sit for 5 minutes or so before serving.