Basil, garlic, pine nuts, Sardinian pecorino — sometimes with grana or parmesan —, extra virgin olive oil and a pinch of salt: pesto is made by pounding everything in a marble mortar with a wooden pestle, always turning the same way, never in a blender according to purists. It dresses trofie, trenette with potatoes, or is thinned with a spoonful of pasta cooking water.
The first printed recipe dates to 1863, in Giovanni Battista Ratto's «La Cuciniera Genovese»: garlic, basil — or, if unavailable, marjoram and parsley —, Dutch cheese and parmesan grated together, pounded into a paste, then thinned with plenty of oil. The Dutch cheese is no mistake: Genoa had intense trade ties with the Netherlands, and a community of Dutch merchants sold their own cheese in the city's markets. A revised version of the recipe, signed by Emanuele Rossi, appeared in 1865.
Basil as the main ingredient appears in the documents only from the middle of the nineteenth century: before that, the Genoese sauce changed with whatever the vegetable garden offered. Today pesto alla genovese is among the Traditional Agri-food Products of Liguria, and Basilico Genovese has Protected Designation of Origin status.