Basil Pesto

Directions

1. 1
   In a blender or food processor, combine the olive oil, walnuts, pine nuts, garlic, and salt; pulse or blend until smooth.
2. 2
   Add the basil in small handfuls, and pulse to combine.
3. 3
   When all the basil has been blended in, transfer to a bowl; add in the Parmigiano-Reggiano and softened butter; mix well to combine.
4. 4
   The olive oil should form a 1-inch layer above the pesto (this keeps the air out, allowing the pesto to retain its vivid color).
5. 5
   Store, covered, in the refrigerator for up to 3 days.
6. 6
   Before using, let come to room temperature and stir well.