Put hazelnuts and garlic in bowl of food processor. Process until nuts and garlic are finely ground. (Approx. 1 minute depending how powerful your processor is.)
Add parsley and process again until finely ground. Scrape down sides midway through if needed. ( Approx. 30-60 seconds)
Pour in olive oil and pulse until mixed.
Add nutritional yeast and salt, pulse until combined and season with extra salt and pepper if needed, to taste.
Notes
Be sure to process the parsley to desired consistency before adding oil. Once the oil is added, the ingredients will be slippery and may not chop well. You can add more or less oil depending on your desired consistency.