50g unsalted butter
200g rindless unsmoked back bacon, diced
3 leeks, trimmed and sliced
2 x 800g butternut squash, skinned, seeded and coarsely diced (about 1kg of flesh once the skin and seeds are removed)
150ml white wine
1.2 litres chicken stock
Sea salt, black pepper
150ml soured cream
1 teaspoon truffle oil
In northern Italy entire restaurants are devoted to truffles, where every single dish is permeated with their scent. Black winter truffles (Tuber melanosporum), summer truffles (Tuber aestivum) and white ones (Tuber magnatum) are used in minute quantities to cast a heady cloak over pasta and risottos, a plate of raw beef or a cheese fondue.
Summer truffles are the most common, and they are the ones we usually encounter here, preserved whole in small jars, but you occasionally see the black winter truffles too – albeit at a price. We can tap into the scent of the white ones courtesy of tiny bottles of pungent truffle-flavoured oil, a few drops of which will leave you with the lingering suggestion of it long after you have finished the last mouthful.
This soup relies on a potato masher rather than a blender, so it's on the rustic side, and that suave little spoonful of cream makes all the difference.
Melt the butter in a large saucepan over a medium heat, add the bacon and fry for 6-8 minutes until lightly coloured and starting to crisp, stirring occasionally. Add the leeks and sauté for about 5 minutes until soft and glossy, and just starting to colour. Add the butternut squash and cook for 10 minutes over a low heat, again stirring occasionally. Pour in the wine and simmer until syrupy and well-reduced. Now add the chicken stock and season with black pepper and a little salt, bearing in mind the bacon will do some of the work. Bring to the boil and simmer for 20 minutes. Using a potato masher, mash the butternut squash until you have a thick, sloppy purée. Taste to check the seasoning.
Blend the soured cream and truffle oil in a small bowl. Serve the soup in warm bowls with the truffle cream spooned in a swirl and a scattering of croutons on top if you wish.
Taken from 'Soup Glorious Soup' by Annie Bell (Kyle Cathie, £14.99).