Bring a large pot of water to a boil and salt well. While the water boils, prep the kale by cleaning it and removing the stalky stems. Add the kale to the boiling water and cook for about 1 minute. Remove with tongs and shock it in an ice bath or under running it under very cold tap water when finished. If you are using the Italian kale pesto now, bring the water back up to a boil to cook the pasta.
Drain kale well and wring out the extra water. If you are cooking pasta, do it now.
In a food processor or with an immersion blender, blend the kale, toasted nuts, garlic, salt, parmesan cheese, if using, and olive oil together to get a smooth, even consistency. Test for salt and pepper.
When the pasta is al dente, drain well, reserving a cup of the starchy cooking water.
Toss the pasta with the Italian kale pesto, adding a bit of the pasta cooking water if it’s too dry or sticking together.
Serve immediately with parmesan cheese or store the pesto in an airtight container in the refrigerator for up to 5 days until ready to use.