To make the gnocchi: Preheat the oven to 400 degrees F. Place the potatoes on a baking sheet and bake until they’re tender when poked with a fork, about 1 hour. When the potatoes are done, immediately slice them open to let the steam out.
Scoop the potato flesh into a potato ricer. Push all of the potato through the ricer into a bowl. (The riced potato should equal about 2 cups.) Sprinkle with 1/4 teaspoon of salt or more, according to taste. Meanwhile, bring a large pot of water to a boil. Add a few pinches of salt.
Sprinkle 1/4 cup of the flour onto your clean counter or cutting board. Knead the potatoes with it, sprinkling in another 1/4 cup flour, until the dough just comes together. If it’s still pretty shaggy, add more flour, 1 tablespoon at a time.
Now for the test! Pinch off a piece of dough and roll it out into a tube. Cut it into a few pieces and drop them into the boiling water to make sure they hold their shape. If they fall apart in the water, knead the dough a bit more. When kneaded just right, the gnocchi will float to the top and look a little ragged, but they should hold together.
Line a baking sheet with parchment. Roll the rest of the dough into ropes that are about 1/2-inch thick, then cut the ropes into 1/2-inch pieces. Transfer the gnocchi to the baking sheet, being sure the gnocchi don’t touch each other. You should have about 40 gnocchi.
Add the gnocchi to the large pot of boiling water in batches of about 10. Adjust the heat so the water doesn’t reach a rolling boil—it should be more like an aggressive simmer. When the gnocchi rise to the surface of the water, they’re done. Remove them with a slotted spoon or mesh strainer and transfer them to a paper towel. drizzle the gnocchi with teeny bit of olive oil (this will prevent them from sticking to one another as they sit).
To make the alfredo sauce: In a medium skillet. set over medium heat, add the butter. When melted, pour in the heavy cream and add the garlic; whisk until emulsified, about 2 minutes. Next, add the diced kale and cook for about 2 to 3 minutes. This will soften the kale and make it nice and tender. Add the Parmesan, diced preserved lemon, crushed red pepper and a few pinches of salt. Mix until the Parmesan has melted. Give it a taste and adjust the salt to taste.
Lastly, add the gnocchi and cook until warmed, about 1 to 2 minutes. Ladle onto plates or bowls and top with a bit more Parmesan and minced Italian parsley.