Bring 3 inches of water with a pinch of salt to a boil in either a deep skillet with a lid or a wide and shallow pot. Remove the stems from the kale leaves, either by slicing along either side of the stem flat on a cutting board, or holding the leaf by the stem and use the "machete" method: using a small sharp knife, slice down the leaf alongside the stem and allow the leaf to fall into the sink basin or your salad spinner. Blanch the kale in the boiling water for 3 minutes, and then quickly cool in an ice bath.
Heat up a cast iron or stainless steel (not non-stick) skillet, and toast the walnuts. A combination of walnuts and pine nuts also works. Allow them just to become golden and fragrant-- as soon as you start to smell the toasty-nutty smell, turn off the heat or they could burn.
In the same skillet, toast the garlic still in its paper shell for 5 minutes, until it become slightly soft. This kills a little bit of its raw bite while still maintaining the flavor. Remove from paper once done. Garlic scapes can also be used instead of cloves (quickly toast in a hot skillet or blanch first.)
Place blanched kale, parsley if using, toasted walnuts, grated cheese, the salt and the garlic in the bowl of a food processor and pulse till shredded. Turn to low, and slowly drizzle about a 1/2 cup of olive oil or sunflower oil in a thin stream. Once it begins to look creamy, stop the blade and taste to see if you need more salt or oil. Scrape down the sides.
Keeps in the fridge for up to 2 weeks or in the freezer for up to 6 months. If adding to hot pasta, add in a tablespoon or so of the pasta water to thin it out.
