Bring a large pot of water to a boil over high.
Heat a large, heavy skillet (preferably cast-iron) over medium-high. Drizzle the scallions with the oil and toss to coat. Add all the scallions to the skillet and weigh them down using a grill press or smaller pot to increase surface contact. Cook for 10 minutes, tossing every 3 minutes or so, until the scallions have significantly reduced in volume, softened and developed dark char marks all over. Transfer the charred scallions to a cutting board.
Add the pasta and a big pinch of salt to the boiling water, and cook until al dente, which is often about 3 minutes less than what the packaging calls for.
While the pasta cooks, coarsely chop the cooled scallions.
Reserve 2 cups of pasta water and drain the pasta. Transfer the drained pasta to the pot and season with a few cracks of pepper.
Stir in the scallions, artichokes, lemon zest and lemon juice. Sprinkle with the Parmesan, drizzle with 1 cup pasta water, then vigorously stir over medium heat until the sauce becomes glossy and creamy. Add more pasta water and salt, if needed, and serve right away.
