Nigella Lawson's garlic and parmesan mashed potatoes

Instructions

• Put the prepared potatoes and garlic into a very large saucepan, cover with cold water, add the salt, put on the lid, and bring to a boil over a high heat, then turn down and cook partially covered – just a crack – until very tender.

• Put a colander over a large bowl or another saucepan and drain the potatoes, letting the starchy water collect underneath. Do not throw this away: it is precious liquid (see recipe introduction).

• Add the butter to the hot, emptied-out potato pan, and let it start melting, then tip in the drained potatoes and garlic. Dip a measuring cup into the cooking liquid, add about ½ cup, and mash using your chosen method (see recipe introduction). You may want to add another ½ cupful or so of cooking liquid. I never add less than 1 cup, as I like this to be as smooth and creamy as possible, though I’m aware many people prefer more solid mashed potatoes. (Again: do not throw away any leftover liquid.) Stir the Parmesan in by hand and check for seasoning before transferring to a warm bowl.

• If you are making this in advance, butter a small roasting pan or ovenproof dish, measuring approx. 9 × 13 inches, and fill with the mashed potatoes, smoothing down the top. Leave to cool, then refrigerate, covered, for up to 3 days. On reheating, remove from the fridge and let come to room temperature, which will take an hour or two, depending on the weather. Preheat the oven to 400°F and make a crumbly topping by rubbing the bread crumbs or panko together with the butter and Parmesan, then dot and sprinkle on top. Cook for about 30 minutes, or until piping hot all the way through. Loosely cover the dish with aluminum foil if the topping is getting too brown at any stage.