Wash the basil leaves and use a paper towel, etc. to properly wipe the moisture.
Add all of the ingredients except for the basil leaves to a blender and mix until smooth.
Add the basil and continue to mix until smooth.
Basil leaves are easily damaged by heat. When making a lot the blender will get hot, so adding the leaves last will help keep their aroma.
To store the paste, pour in about 1 cm of olive oil to the top. This keeps it from oxidizing and changing color.
Additional Note: I wrote 3-5 g for the salt amount. 3 g is the regular amount, and 5 g gives it a strong saltiness, good for eating as-is with bread or potatoes.
Adjust the amounts as you see fit. If adding powdered cheese, 3 g of salt should be enough.
Story Behind this Recipe
We make a lot of basil every year. Upon harvesting it, I make this sauce. I used to make this with pine nuts, but I wasn't able to buy them in time, so I used walnuts as a replacement. I gradually phased out the pine nuts and now only use walnuts. It's just as delicious, and cheaper, so now I make it with walnuts.
Lightly roast the walnuts beforehand, taking care not to burn them. Let them cool. This can also be frozen. I put a little into a small container and froze batches. Thaw out the amount you plan to use, and use it as quickly as possible. After thawing be sure to put it back in the freezer.