Put the basil leaves, garlic, pine nuts, and a tiny bit of sea salt into the food processor. Turn it on and begin drizzling in the olive oil, blending well. Scrap the sides of the food processor.

Taste and adjust the salt (but use a very light hand, because you’re still going to be adding cheese). If you are making this batch to freeze, never add cheese at this point. You’ll freeze it without cheese and add cheese when you thaw it out for your pasta.

Assuming you’re eating it tonight, stir in the grated cheeses and use the pesto for the pesto chicken recipe. But if you’ve made the pesto for pasta, here’s what you should do: before you drain your pasta, reserve a cup of the pasta water. Drain the pasta in a colander and put it back in the hot pot. Add the pesto, toss well with a couple tablespoons of unsalted butter. Then add the cheeses. Toss again and add a little of the pasta cooking water to thin the pesto slightly so that it will coat the pasta like silk. Serve with additional grated Parmigiano-Reggiano cheese.