Preheat the oven to 180°C / 350°F / Gas Mark 4.

In a large frying pan, heat the olive oil, and add the onion, carrot, celery and garlic. Cook over a gentle heat for 3-4 minutes, then add the mushrooms and courgette. Cook for a further 5 minutes. Add the passata and beans, and simmer for 10 minutes.

Meanwhile, bring a large saucepan of salted water to the boil, add the pasta shells and cook according to packet instructions. Drain, then return to the pan and cover with cold water to stop them sticking together.

Remove the bolognese from the heat, throw in the spinach, and blitz with a hand/stick blender, (you are aiming for a mix of chunks and thick sauce, not baby food purée, so just pulse a couple of times!).

Oil a large ovenproof dish (similar to a lasagne dish), and start to fill the shells. Take each shell in one hand, squeeze to hold it open, then fill with one dessert spoon of bolognese. Place in the dish with the crease at the bottom. (You can tesselate your shells into a pretty pattern, or just throw them in - entirely up to you!).

When all the shells are stuffed and in the dish, pour the cheese sauce over the whole lot, then scatter with the breadcrumbs and vegetarian parmesan. Bake for 20 minutes or until golden brown on top and bubbling underneath.

Serve with a crisp green salad.