The Best Pesto alla Genovese (Classic Basil Pesto Sauce) Recipe

Using a mortar and pestle, combine garlic and sea salt and grind to a paste. Add pine nuts and continue to crush with pestle, smashing and grinding them, until a sticky, only slightly chunky, beige paste forms. Add basil leaves, a handful at a time, and pound and grind against the walls of the mortar. Continue until all basil leaves have been crushed to fine bits. Add both cheeses, then slowly drizzle in olive oil, working it into the pesto with the pestle until a fairly smooth, creamy, emulsified, sauce forms. Add more oil, if desired. Pesto can be served with pasta right away, or transferred to a jar or container, covered with a small layer of olive oil, sealed, and refrigerated overnight.