'Genoese pesto') is a paste made of crushed garlic, pine nuts, salt, basil leaves, grated cheese such as Parmesan or pecorino sardo, and olive oil.

The ancient Romans used to eat a similar paste called "moretum", which was made by crushing garlic, salt, cheese, herbs, olive oil, and vinegar (and sometimes pine nuts) together.

[3][6] The use of this paste in the Roman cuisine is mentioned in the Appendix Vergiliana, an ancient collection of poems in which the author details the preparation of moretum.

Emanuele Rossi published La Vera Cucineria Genovese in 1852 and gastronomist Giovanni Battista Ratto published La Cuciniera Genovese in 1863:[3] "Take a clove of garlic, basil or, when that is lacking, marjoram and parsley, grated Dutch and Parmigiano cheese and mix them with pine nuts and crush it all together in a mortar with a little butter until reduced to a paste.

First, garlic and pine nuts are placed in the mortar and reduced to a cream,[2] and then the washed and dried basil leaves are added with coarse salt and ground to a creamy consistency.

[13] Pesto is commonly used on pasta, traditionally with mandilli de sæa ('silk handkerchiefs' in the Genoese dialect),[14] trofie or trenette.

[15] The original pesto alla genovese is made with Genovese basil, coarse salt, garlic, Ligurian extra virgin olive oil (Taggiasco), European pine nuts (sometimes toasted), and a grated cheese such as Parmesan or Grana Padano and pecorino sardo or pecorino romano.

[13] A proposal is under preparation by the Palatifini Association to have pesto alla genovese included in the UNESCO intangible cultural heritage list.

[20] Any combination of flavourful leaves, oily nuts, hard cheese, olive oil, garlic, salt, and lemon juice can produce a pesto-like condiment.

[22] Outside Italy, the name pesto has been used for all sorts of cold sauces or dips, mostly without any of the original ingredients: coriander, dill, kale, mint, parsley, rocket, spinach, or wild garlic (instead of or in addition to basil), artichokes, black olives, green olives, lemon peel, lime peel, or mushrooms.

A Peruvian variety, known as tallarines verdes[25] (meaning 'green noodles', from Italian tagliarini), is slightly creamier, lacks pine nuts (because of their rarity and prohibitive cost in Peru), may use spinach and vegetable oil (in place of olive oil), and is sometimes served with roasted potatoes and sirloin steak.