Bring a large pot of generously salted water to a rolling boil. Cook the mafaldine according to package directions until al dente. Reserve 1 cup of the starchy pasta water, then drain the pasta.

While the pasta cooks, melt the butter in a large skillet over medium heat. Add the minced garlic and cook until fragrant, about 1 minute, without browning. Pour in the heavy cream and bring to a gentle simmer. Stir in the lemon zest and juice, then reduce heat to low.

Remove the skillet from the heat. Whisk the grated Parmesan into the cream mixture until melted and smooth. Add the cooked mafaldine directly to the skillet. Toss vigorously with tongs, adding splashes of reserved pasta water a little at a time until the sauce becomes silky and clings to each ribbon. Season with salt and pepper.

Remove from heat and fold in half the basil. Divide among warmed bowls, shower with extra Parmesan, a few cracks of black pepper, the remaining basil, and a whisper of lemon zest if desired. Serve immediately.