‘I’m a famous chef – never pour potato water down the drain – instead do this’

has shared a simple yet effective that could change the way people .

The celebrity chef says the water used to boil potatoes should never be poured down the drain. Instead, she recommends keeping it to make “the best vegetable soup in the world.”

The advice appears in her cookbook , where she shares practical tips alongside her signature recipes.

The tip also reappears in her where she explains that the starchy water left behind after boiling potatoes is a valuable ingredient.

Rather than wasting it, she suggests using it as a base for a by cooking frozen petits pois in the liquid before blending until smooth.

The result, she claims, is so delicious that throwing the water away would be a mistake.

She also says that it can be stored in the fridge for up to five days, making it easy to use later.

Nigella also incorporates the water back into her mashed potatoes, insisting that at least 250ml should be added for a smooth, creamy texture.

While some may prefer a firmer mash, she argues that the potato water helps achieve the best consistency.

She also suggests boiling garlic cloves with the potatoes, which gives the mash a subtle sweetness without overpowering the dish.

Beyond soup and mash, the starchy water has other uses. Some home cooks use it to thicken sauces, add depth to bread dough, or even as a natural plant fertiliser due to its nutrients.

Nigella also shares a clever way to use up leftover mash – pressing it into a waffle maker to create crispy potato waffles, which she says make a great alternative to hash browns.

The full for Nigela’s Garlic and Parmesan Mash:

Ingredients:

• 2kg potatoes, such as Maris Piper, peeled and cut into large equal-sized chunks
• 8 fat garlic cloves, bruised and slightly splintered with the flat side of a wide-bladed knife, then slipped out of their skins
• 2 tsp sea salt flakes, plus extra to taste
• 75g unsalted butter, softened
• 50g Parmesan, finely grated

For the optional topping:

• 50g dried breadcrumbs or panko
• 50g unsalted butter, in blobs or teaspoons
• 35g Parmesan, finely grated

Method:

1. Put the prepared potatoes and garlic into a very large pan, cover with cold water, add the salt, cover with a lid and bring to the boil over a high heat. Turn down and cook partially covered – just a crack – until very tender.
2. Place a colander over a large bowl or another pan and drain the potatoes, letting the starchy water collect underneath. Do not throw this away: it is precious liquid.
3. Add the butter to the hot, emptied-out potato pan and let it start melting. Tip in the drained potatoes and garlic.
4. Dip a measuring cup into the cooking liquid and add about 125ml before mashing the potatoes. More liquid can be added depending on the preferred consistency. Nigella recommends using no less than 250ml for the creamiest results.
5. Stir in the Parmesan by hand and check for seasoning before transferring to a warm bowl.

Crumb topping:

1. Butter a small roasting tin or ovenproof dish, measuring approx. 30x25cm/12x10in, and fill with the mashed potatoes, smoothing down the top. Leave to cool, cover, and place in the fridge for up to three days.
2. Remove from the fridge and allow to come to room temperature before reheating.
3. Preheat the oven to 200C/180C Fan/Gas 6.
4. Make a crumbly topping by rubbing the breadcrumbs together with the butter and Parmesan, then dot and sprinkle on top.
5. Cook for about 30 minutes, or until piping hot all the way through. If the topping browns too quickly, loosely cover with foil.