Fill a large pot with water (about 4 quarts) and plenty of salt (about 2 tablespoons, this helps season the pasta, you won’t be eating all of it!) and bring to a boil. Add pasta and cook until al dente. Reserve 1 ½ cups of the pasta water before draining. Drain pasta and set aside.
In a large skillet over medium heat, add the olive oil. Once the oil is hot, add the black pepper and red pepper flakes (if using) and let cook for 30 seconds, stirring constantly (to toast the spices). Stir in the white scallions and ½ tsp salt and cook for 3 minutes, until the scallions have softened.
Add the corn and cook for another 3-4 minutes, or until the corn is tender (it will take a minute or so longer for frozen corn). Turn off the heat and transfer to a blender with ½ cup tap water and blend into a thick mixture, with some corn chunks remaining (this will happen fast).
Return the skillet to medium-high heat and pour the corn back in along with 1 cup tap water, kale, and remaining ½ teaspoon salt and cook for 2-4 minutes, stirring often to submerge the kale, or until the kale softens/wilts. Add the drained pasta, 1 cup reserved pasta cooking water, green parts of scallions, and butter and toss to coat (tongs are best), until a glossy, thick sauce forms and coats the noodles, about 3-5 minutes. Add splashes of pasta water if the sauce is looking too dry. Stir in the lemon juice. Season with more salt and pepper, to taste.
Serve topped with plenty of parmesan and black pepper.