Liguria, particularly the inland hill towns. Walnut trees are abundant in the Ligurian Apennines and the sauce is one of the oldest documented Ligurian preparations, appearing in 16th century manuscripts as an accompaniment to fresh pasta.
A cold walnut sauce made from blanched walnuts, soaked bread, garlic, marjoram, prescinseua or ricotta, Parmigiano, and olive oil — ground by mortar or blender to a thick, creamy paste used to dress pansoti, trofie, or as a bruschetta topping. The technique of blanching walnuts to remove their bitter paper-like skin is essential — it transforms a harsh, tannic flavour into something sweet, rich, and creamy.
Blanched walnuts have a creamy, mellow sweetness without the harsh bitterness of raw walnuts. Combined with marjoram's floral-herb note and the subtle dairy of prescinseua, the sauce is rich, aromatic, and deeply satisfying — among the most distinctive and underrated sauces in Italian cooking.
Walnuts must be blanched (submerged in boiling water for 2 minutes) and then the thin inner skin rubbed off while still warm. This is time-consuming but transforms the sauce. Soaked bread (crustless, soaked in milk and squeezed) adds body and creaminess without flour. The prescinseua (Ligurian curd) or ricotta provides a dairy richness and slight acidity. Garlic is used minimally — 1 small clove per 100g walnuts — and it should be crushed, not minced, and removed if the flavour is too assertive. Work the sauce in a mortar for texture, or briefly in a blender if a smoother result is desired.
If prescinseua is unavailable, full-fat ricotta works well with a teaspoon of natural yoghurt for acidity. The sauce should be made at the last possible moment — walnut oils oxidise within hours and the sauce darkens. If making ahead, press plastic wrap directly against the surface to exclude air. Thin with pasta water to achieve the coating consistency needed for fresh pasta.
Using un-blanched walnuts — the tannins make the sauce bitter and grey in colour. Too much garlic — overpowers the delicate walnut flavour. Not enough body from the bread — the sauce is too thin to coat pasta. Using stale or rancid walnuts — their oxidised oils make any sauce inedible. Skipping the marjoram — it is the herb signature of Ligurian cuisine and defines this sauce.
Giorgio Locatelli, Made in Italy; Slow Food Editore, Liguria in Cucina