Pesto freezes very well, but keep in mind that if you plan on freezing it, omit the cheese and add it only when you are ready to use the pesto. Use the ingredient measurements more as a guideline depending on the quantity of basil you are using.
- 8 cups loosely packed basil leaves
- ¼ cup pine nuts
- 2 garlic cloves, peeled and trimmed of tough ends
- ½ teaspoon salt
- 1/3 cup extra-virgin olive oil (more if necessary)
- ¼ cup freshly grated Parmigiano-Reggiano
- ¼ cup freshly grated Pecorino Romano or Pecorino Fiore Sardo
- Remove the basil leaves from the stems and wash them in cold water. Spin the leaves dry in a salad spinner and lay them on a clean dish towel to air-dry for 20 minutes. Blot away any remaining moisture using paper towels. Set aside.
- Heat a small skillet over medium heat. Toast the pine nuts in the dry skillet tossing continuously, until the pine nuts are light golden brown and fragrant. Transfer the nuts to a plate to cool completely.
- Place the basil leaves, pine nuts, garlic cloves, and salt in the bowl of a food processor fitted with the steel blade. Pulse a few times to coarsely chop all the ingredients. With the machine running, stream the olive oil through the feed tube until the pesto is smooth and thick in consistency (it should not be gloppy or runny). Scrape down the sides of the bowl to ensure all the ingredients are evenly incorporated.
- If you will be using the pesto immediately: Transfer the pesto into a serving bowl large enough to accommodate the amount of pasta you are making and stir in the cheeses. As the pasta finishes cooking, ladle out about ½ cup of the hot pasta water into a heat-proof measuring cup and set it aside. Drain the pasta through a colander, add it to the serving bowl, and toss to coat the pasta evenly with the pesto. If the sauce seems too thick, dribble in small amounts of the pasta cooking water to thin the sauce gradually. It should take on a creamy consistency and cling to the pasta evenly.
- Storage: If you will not be using the pesto right away, transfer it into freezer-safe containers and smooth the top surface with a spatula. Cover the top completely with a thin layer of olive oil and close the container tightly. Refrigerate and use within 3 days, or freeze for up to 3 months. You can also transfer the pesto sauce into an ice cube tray if you want to have smaller portions. Once the pesto cubes have solidified, pop them out and transfer them into a freezer-safe zip bag and return to the freezer.