Bring a large pot of water to a boil and salt well. While the water comes to a boil, clean the kale, removing the stalky stems and roughly chop.
Peel and smash the garlic gloves. Heat the olive oil in a small skillet over low heat and add the smashed garlic. Cook for just a couple of minutes to infuse the olive oil, being careful not to burn the garlic. It should not brown, just get golden.
Add the kale to the boiling water and cook for 4 minutes.
Remove the kale with a pair of tongs and transfer it to a bowl or a blender. Add the garlic and olive oil, parmesan cheese, if using, and ¼ teaspoon salt.
Add the pasta to the boiling salted water and cook al dente.
Blend the kale sauce using an immersion blender or blender. Test for seasoning and add salt and pepper, if need be (the amount of salt you add will depend on how salty your pasta cooking water was to begin with).
Drain the pasta, reserving a cup of the starchy water.
Return the al dente pasta to the pan and toss with the creamy kale sauce, adding a bit of the reserved starchy pasta water if it’s too dry or sticky. Serve immediately with more grated parmesan cheese.