Step 1

Place the walnuts and garlic in the bowl of a food processor fitted with a steel blade. Process until coarsely chopped, about 10 seconds. Add the basil leaves, salt, and pepper and process until mixture resembles a paste, about 1 minute. With the processor running, slowly pour the olive oil through the feed tube and process until the pesto is thoroughly blended. Add the Parmesan and process a minute more. Use pesto immediately or store in a tightly sealed jar or air-tight plastic container, covered with a thin layer of olive oil (this seals out the air and prevents the pesto from oxidizing, which would turn it an ugly brown color). It will keep in the refrigerator for about a week.

Step 2

Freezer-Friendly Instructions: Pesto can be frozen in an airtight container for up to 6 months. You can also divide your prepared pesto into the compartments of an ice cube tray and freeze. Once it’s frozen, remove the pesto cubes from the tray and put in a sealable plastic bag or airtight container. You can add the defrosted pesto cubes to soups, pasta dishes, eggs, sandwiches, and potatoes.