Nutmeg I actually grate

The mash is almost ready, the milk is in, the butter has melted, and my hand reaches for the fine grater and the whole nutmeg in the jar. I could shake in ground nutmeg from the packet and call it done. Instead I give it two or three strokes straight over the pan, and the smell changes at once: warm, a little sweet, gone almost as soon as it arrives.

That is the whole point of a whole nutmeg. Ground nutmeg starts losing its scent from the day the packet is opened, and after a few months in a warm cupboard it smells of very little. A whole nut keeps its oils locked inside until the grater opens them, so every grating is as fresh as the first. If my jar of ground nutmeg smells of cardboard when I open it, I don't argue with it. I grate fresh.

In our kitchen nutmeg has a few jobs and I don't ask it to do more. Cinnamon goes with apples, paprika goes with onions, bay leaves go into soup and come out again. Nutmeg goes into mash, into a white sauce, into anything with milk or cream that needs rounding off. It is not a spice for every pot in turn.

Here is how I do my mash. I peel about a kilo of floury potatoes, Maris Piper or King Edward, cut them into even chunks and put them in a pan of cold salted water. I bring it to the boil and simmer for about twenty minutes, until a knife slides in with no resistance. While they cook I warm a hundred millilitres of milk with fifty grams of butter in a small pan, just until the butter melts. I drain the potatoes well and let them steam in the colander for a minute or two, because wet potatoes make a heavy, gluey mash. Back in the pan, I mash them while they are still hot, pour in the warm milk and butter and beat with a wooden spoon until smooth. Then the salt, and then the nutmeg: two or three strokes on the fine side of the grater, a stir, a taste. If I can name the nutmeg straight away, I have used too much. It should sit quietly behind the potato and the butter.

A white sauce works the same way. I melt butter, stir in the same weight of plain flour, cook it for a minute without letting it colour, then whisk in warm milk a little at a time until it thickens. A small grating of nutmeg goes in at the end with the salt. It is the nutmeg that makes a white sauce for lasagne or cauliflower cheese taste finished rather than floury. Sometimes I add a whisper of it to morning porridge with milk, on the tip of a knife, no more.

I never heap it. Nutmeg turns bitter quickly when there is too much, and it is a spice to be used in small amounts in any case, not by the spoonful. A whole nut lasts a long time at a few gratings a meal, so I keep one or two in a small jar with a tight lid, away from the hob and the kettle steam, and I don't buy a fistful to last for years. When a nut gets small, I hold the last piece carefully against the grater and keep my fingers well away from the teeth.

The grater matters too. I use the finest side of an ordinary box grater, or a small rasp, and I grate straight over the pan so that nothing is lost on the board. A quick tap on the edge of the pan knocks the last of the dust in.

I don't need a nutmeg museum on the shelf. I need a few gratings that make the mash smell warm. In your house, does the nutmeg make it to the grater, or does it sit ground in a jar until it loses its scent?