Place the dried porcini mushrooms into a large bowl and pour over one-fourth cup boiling water. Soak for 15 minutes.

Crumble vegetable stock cube, or pour the powder, into two and a half cups boiling water.

Heat olive oil in a shallow skillet or deep frying pan over a medium flame. Add the onion and garlic, then fry for about five minutes until soft.

Stir in the chopped chestnut mushrooms and the rehydrated dried porcini mushrooms with water. Season with salt and pepper and continue to cook for eight minutes until the fresh mushrooms have softened.

Tip the risotto rice into the pan and cook for one minute. Pour over Baron Herzog Pinot Grigio wine and let it bubble away, so the alcohol evaporates.

Keep the pan over a medium heat and pour in a quarter of the vegetable stock. Simmer the rice, stirring often, until the rice has absorbed all the liquid.

Add about the same amount of stock again and continue to simmer and stir – it should start to become creamy, plump and tender. By the time the final quarter of stock is added, the rice should be almost cooked.

Continue stirring until the rice is cooked. If the rice is still undercooked, add a splash of water. Take the pan off the heat, add butter or margarine and scatter over half the parmesan.

Cover and leave for a few minutes so that the rice can take up any excess liquid as it cools a bit. Stir in the walnuts.

Give the risotto a final stir, spoon into bowls and scatter with the remaining parmesan, chopped basil leaves and a drizzle of truffle oil.