Mince the garlic cloves in the bowl of a food processor then add the walnuts and roughly chop. Add about half of the arugula and the walnut oil and pulse until combined. Add the remaining arugula, salt, and pepper, and with the blade running, drizzle in olive oil until pesto is creamy but thick like ketchup. Store in a covered container in the refrigerator for up to 3 days or freeze.
Notes
Many pestos include grated cheese. I prefer to leave the cheese out when making pesto and freezing it and adding it later when I'm using the pesto in a finished dish.
Recipe by Cooking With MicheleĀ® at https://cookingwithmichele.com/2013/06/arugula-walnut-pesto-with-roasted-garlic/