3 cups loosely packed carrot peels (from about 3 to 4 pounds carrots)
1/2 cup coarsely chopped toasted walnuts
1/2 cup grated Parmesan cheese
1 clove garlic
1/4 teaspoon kosher salt
1/4 to 1/2 cup extra-virgin olive oil
Place the carrot peels, walnuts, cheese, garlic, and salt in a blender or food processor fitted with the blade attachment. Blend or process until the ingredients are finely chopped and a rough paste has formed. Stop and scrape down the sides of the jar or bowl as needed.
With the motor running, stream in the olive oil: 1/4 cup will make a thicker pesto that’s good for spreading on crostini and sandwiches, while 1/2 cup will make a thinner pesto that’s good for tossing with pasta. Stop and scrape down the sides of the jar or bowl as needed and blend until the mixture is a uniform paste.
Taste the pesto and blend in more more salt, garlic, nuts, or cheese as needed.