This creamy soup uses five of the best winter vegetables, and it’s very easy to make. Don’t worry about precise quantities, but use the list here as a rough guide.

Steps

1. Peel and chop the onion. Clean the leeks and slice them about ⅜-inch thick.
2. Put the butter and oil in the saucepan and turn the heat to low. Add the onion and leeks, cover, and cook the vegetables gently for a few minutes so that they soften.
3. Peel the potatoes and cut into small cubes. Cut the thick stem out of the cauliflower and discard it. Break the cauliflower into florets.
4. At the last minute, peel the celery root thickly so that you’re left with just the white flesh (like a banana, celeriac turns brown very quickly once it’s been cut). Chop this into cubes and add to the pan with the cauliflower and potatoes as well as the stock, a pinch of salt, and a twist of pepper. Stir well and bring to a boil, then reduce the heat and simmer gently until the vegetables are tender; 15 minutes should be enough.
5. Stir in the cold milk, then turn off the heat and let the soup cool for at least 15 minutes. Purée the soup in the blender, a few ladlefuls at a time. You can either reheat it now, to serve immediately, or chill it in the fridge and use within 5 days.
6. Return the soup to the pan, stir in the cream, and reheat gently but thoroughly. It doesn’t need to boil again, but it should be piping hot. Check the seasoning and add more salt and pepper if necessary.
7. Serve just as it is or, if you like, with an extra swirl of cream and some chopped chives. Some bread would be nice, too.