Preheat oven to 350°F. Lay walnuts on sheet pan and bake for 5-7 minutes, until slightly toasted. Let cool.
Clean basil and dry. We like using a salad spinner to dry the basil because it prevents bruising to the leaves.
Add juice of ½ lemon, walnuts, and garlic cloves to blender and blend well. Add basil and slowly add oil while blending. Stop when all ingredients are fully incorporated. Add crushed red pepper, salt, and pepper, blend for 2-3 seconds. Add Parmesan cheese and blend. Store in air tight container with small layer of olive oil on top to help preserve green color.
Notes
Pesto freezes very well so it makes a perfect recipe to make in bulk when basil is in season and portion it for later use. I use a silicon ice cube tray to freeze individual portions of pesto that I can grab when needed. Simply spray tray with non-stick spray, add pesto, then add a small layer of oil on top. Put in a freezer bag or seal with plastic wrap, let freeze, then remove and add to a freezer bag for storage. You can held the pesto for up to 6 months in the freezer.Basil leaves weigh about 25 grams per cup when removed from the stem. I like weighing basil instead of putting it in a measuring cup because the compacting will cause the basil to bruise and turn black. This recipe uses about 60 grams of basil.