Rachel Roddy's recipe for spaghetti with lemon, parmesan and cream

Lemons are many things, and January is a good time to fill a bowl with half a dozen. Take one, dig your nail into its oily, open-pored skin, sniff and make a mental list. Lemons are also full of particles with a positive electric charge, which, when on the loose, are like teenage boys in a brand new electric car, cruising around looking for other molecules to attach to, and in doing so they change them. It is this concentrated proton activity that the nerves in the tongue and brain interpret and experience as the sensation of sourness when they encounter lemon.

We studied this at school, and also stuck copper wire in oval fruits with nipples in order to make a lemon battery. However, it was rereading Margaret Visser’s tart and witty chapter on lemons in her book Much Depends on Dinner that reminded me of the science; how the movement and proton pumps result in the formation of citric acid, which explains much. Lemons are not just handy, long-lasting, perfectly packaged, sunny, essential, beautiful and so on, they are charged, they are jump leads, they are a sort of edible electricity. No wonder we get such a thrill from a wayward spritz of juice that hits an eye, a twist or a slice.

January, particularly this January, is a good time to make spaghetti with lemon, parmesan and cream; a smooth and sharp dish that is also useful in that the sauce takes almost exactly the same amount of time to prepare as the pasta takes to cook.

Don’t worry about the lemon juice splitting the cream; by melting the butter with the lemon juice, grated zest and slivers over a low heat, you create a pretty stable emulsion to which the cream can be added, and the parmesan thickens further, but remember to the keep the heat under the pan low and gentle. Another thing to remember is not simply to toss, but to really swish the pasta when you add it to the pan, so the starch is released and jolted into the butter and cream sauce, which helps it to thicken and, in turn, cling to the stands of spaghetti.

We don’t need science to tell us that lemon juice is a great awakener; just a few drops can bring out other flavours and heighten our appreciation of them. It might sound like overkill, but spaghetti with lemon, parmesan and cream is even better when followed by a green salad in an olive oil, salt and lemon dressing (I shake them in a jam jar with a drop of water), and better still if you have a slice of chocolate cake for pudding.

Spaghetti with lemon, parmesan and cream

Serves 4

2 unwaxed lemons
Salt and black pepper
450g spaghetti
50g butter
12
0 ml single cream
1 small garlic clove, peeled and crushed but whole
4 heaped tbsp grated parmesan

Bring a large pan of water to a boil for the pasta. Using a vegetable peeler, pare the rind (and as little pith as possible) from one lemon, then cut the pared strips into very thin slivers. Grate the rind from the other lemon, then squeeze out the juice.

Once the water boils, add salt, stir and add the spaghetti, setting the timer for a minute less than the recommended cooking time.

While the pasta cooks, in a wide frying pan over a medium-low heat, warm the butter with the lemon slivers and and two tablespoons of lemon juice. Once the butter is foaming gently, stir in the cream and two tablespoons parmesan, and bring up to a bubble. Turn the heat to low and keep warm.

Once the timer for the pasta goes, drain, reserving some of the cooking water (or lift it directly into the frying pan with tongs), then toss in the creamy sauce and swish vigorously so the starch from the pasta combines with it. Add the rest of the parmesan and a few grinds of black pepper, and toss again so the sauce clings to the strands; if it seems stiff, add a little of the reserved water and stir again. Serve immediately.