• Add basil, parsley, Parmesan cheese, walnuts, and garlic in a food processor or blender. Pulse until coarsely chopped, about ten pulses.
• With the motor running, slowly drizzle in the olive oil and process until smooth—season to taste with salt and pepper.

Notes

1. Parsley: Basil can quickly turn brown in a food processor from bruising. Add a handful of fresh parsley to preserve the bright green color.
2. Walnuts: For more flavor, toast the walnuts. Heat walnuts in a medium skillet over medium heat until browned and fragrant, occasionally stirring, about 2 to 5 minutes.
3. Garlic: Roasting garlic trades its raw heat for a mellow taste and soft texture. To try this option, toast unpeeled garlic cloves until spotty, dark brown, and slightly softened for about 20 to 25 minutes in a dry medium skillet over medium-low heat.
4. Yield: This recipe makes 1 cup of pesto, enough to dress 1 pound of pasta.
5. Storage: Store covered in the refrigerator for up to 4 days (add a layer of olive oil on top to prevent oxidation).
6. Freezer: Pour into a jar and top with olive oil to prevent oxidation. Leave enough head space at the top of the jar for expansion, then freeze for up to 6 months—thaw overnight in the refrigerator.
7. More nuts: Traditional pesto sauce is made with pine nuts, or you could substitute an equal amount of almonds, pecans, cashews, or even hazelnuts.
8. Spicy: Add 1/4 teaspoon or more crushed red pepper flakes to the food processor before blending.
9. Kale pesto: Omit the parsley, decrease the basil to 1 cup, and add 2 cups of packed kale leaves. Proceed with the recipe as written.
10. Pesto roasted chicken: Rub pesto under and on the skin of your next whole bird, then toast to perfection.
11. Pesto cheese bread: Slice a loaf of bread in half lengthwise, then spread a thick layer of pesto. Top with cheese, then finish in the oven or on the grill.
12. Cavatappi: Try with a splash of cream and fresh tomatoes.