In a food processor, place all the ingredients, except from the olive oil, and blend into a paste texture.
While the food processor is running, add the olive oil gradually until you reach the consistency you prefer. If you want a more thin pesto, add more olive oil. Taste and adjust seasoning if needed.
Transfer to a jar and refrigerate for up to 10 days. To maintain the pesto bright green color, add a little olive oil to the jar after each use, making a layer of protection from the air.
Notes:
You can veganize the pesto by excluding the parmesan cheese. In that case, I would mix the walnuts with cashews or other kind of nut for more deep flavors.
If you find the taste of kale alone too strong (or if you just want to vary)- swap half of the kale for basil. tasty.
For kale pest pasta- just mix the pesto in a pan with about half a cup of the pasta cooking water on medium heat for about 2 minutes, then add the cooked pasta and mix until full cover for another minute. You can scrape more parmesan over the serving.