The potted basil on the back stoop, put in unusually late this year, has finally matured enough to harvest a few precious leaves—about half a cup packed down—just right for a single serving of pesto alla genovese.

It promptly went into my small marble mortar with about a half-teaspoon of chopped garlic, a generously rounded teaspoon of pine nuts, and a generous pinch of salt. I started grinding, not beating, with the mortar in an even, rotating motion, crushing everything against the sides and bottom of the mortar. With surprisingly little time and effort, it quickly became a thick, brilliant-green paste.

Next I worked in a very small handful of Parmigiano-Reggiano and tasted—and my heart sank: that pinch of salt shouldn’t have been quite so generous. But since there was no way to correct it short of finding a neighbor with more basil, I had no choice but to brook the disappointment and press on.

Hoping for good karma, I switched to a small wooden spoon given to me by the Genoese woman who had taught me to make this fragrant sauce, and began beating in good olive oil by droplets until the paste was smooth and creamy. I tasted (still too salty) and, hoping for the best, put it aside for its flavors to meld.

There’s a lot of posturing about “absolute freshness” being the key difference between a good pesto and a great one, and the reason you should never buy the manufactured stuff. Well, the reason you should never buy the manufactured stuff is that it’s often made with inferior ingredients and is mostly not all that good. A really good pesto benefits from being allowed to mellow for a bit after it is made.

When it was time for dinner, I put on the water for the pasta and, because the sauce was over-salted, compensated by adding only a little salt to the pot. I stirred in a good handful of thin spaghetti, and turned back to the pesto, scraping it into a roomy serving bowl and adding a lump of softened unsalted butter.

Just before taking up the spaghetti, I put a couple of spoonfuls of its cooking water into the pesto and mixed it in. The softened butter stayed thick, like sour cream, and I whipped the whole together with a wooden spoon to the consistency of thick fresh cream.

The sauce glided luxuriously over the long noodles, its irregular bits of basil as vibrant and fresh as a soft summer morning, its spicy fragrance filling the air as it warmed.

Holding my breath a little and still expecting a sharp edge of too much salt, I took a small bite. As it melted on my tongue and that fragrance filled the corners of my imagination, years fell away and I could almost feel the warm sea-tinged breeze of the late summer afternoon when I first tasted this little piece of Genoese magic. It was perfectly balanced, silky-rich and spicy yet so smooth that it could even stand a sprinkling of fresh Parmigiano. Being stingy with salt in the pasta cooking water and using unsalted butter to finish the sauce had done the trick.

Settling in, I let that fragrance and flavor take my imagination back to a time when my senses were fresher, less jaded, and every mouthful was an adventure.

Pesto alla genovese

The name for this sauce supposedly comes from the way it was originally made—with a mortar and pestle. The food processor has made pesto alla genovese commonplace for us—almost too commonplace for our own good. While it makes a perfectly respectable sauce, the machine really doesn’t save all that much time and elbow grease. And its flavor is never as developed as a sauce that is made by gradually working it to a paste with a mortar and pestle. You really should make it by hand at least once in order to fully appreciate pesto at its very best.

Historically Genoese cooks used only Pecorino Sardo (a mellow Sardinian sheep’s milk cheese) in pesto. Today it’s used in equal parts with Parmigiano-Reggiano, but it’s a mellower and less assertive cheese than the more commonplace Pecorino Romano that’s so widely available to us. To maintain the right balance, use one part Romano for every three parts of Parmigiano. For a mellower sauce, you can leave out the Romano altogether.

Pesto is traditionally paired with long, narrow homemade egg noodles called trenette, or with dry factory pasta such as linguine or spaghetti. It is also used to sauce gnocchi, lasagna, and corzetti (coin-shaped stamped pasta) and a spoonful is often stirred into the Ligurian version of minestrone. The Genoese frequently add a few boiled haricots verts and sliced potatoes to trenette that is sauced with pesto.

Makes about 2 cups, enough for 6-8 servings

Salt

2 large cloves garlic, lightly crushed, peeled, and chopped

2 tablespoons pine nuts (or roughly chopped pecans)

2 firmly packed cups small basil leaves, preferably the small-leaved Genoese basil

½ cup extra virgin olive oil

½ cup freshly grated Parmigiano Reggiano

(Optional) 2 tablespoons freshly grated Pecorino Romano

2 tablespoons unsalted butter, softened, for serving

1. Put a large pinch of salt, the garlic, pine nuts, and a handful of the basil into a mortar. In a smooth, rotating motion, work it to a coarse paste with the pestle, crushing (not pounding) everything against the sides and bottom of the mortar. Add the remaining basil in handfuls and gradually work it to a paste.

2. Add the cheeses and continue working with the same rotating motion until it’s a thick, consistent paste. Scrape everything that’s stuck to the pestle into the mortar and set the pestle aside. Switching to a wooden spoon, gradually beat in the oil a few drops at a time until the pesto is smooth. You may need a little more or less oil, depending on your taste and the consistency of the other ingredients.

3. Let the pesto rest for at least an hour before using. Our cook at the school made it a day ahead, floated a thin layer of oil on top to keep it from discoloring, and let it mellow overnight in the pantry. Scrape it into a jar and add an eighth-inch layer of olive oil, then cover and let it sit at room temperature for up to eight hours. For longer storage, refrigerate it, but know that it will never be quite as good after it has been chilled.

4. To sauce pasta with pesto, cook the pasta in four quarts of water until it is al dente (the time will depend on the type and shape used). Allow a generous tablespoon of pesto per serving, and an extra spoonful for every three or four servings for good measure. Just before draining the pasta, put the butter into the pesto and stir in a few spoonfuls of the pasta cooking liquid until it is the consistency of thick cream. Drain and add the pasta and toss until it is evenly coated. Serve immediately, passing more freshly grated Parmigiano-Reggiano separately.