1/2cup grated Parmesan cheese (about 2 ounces), plus more for serving
Instructions
Bring a half-full pot of water to a boil and salt it. Melt the butter in a large skillet over medium heat. Add the garlic and red chile flakes if you’re using them. Cook, stirring occasionally, until golden and fragrant, 2 to 3 minutes. Add the tomatoes and sprinkle with salt and pepper.
Adjust the heat so the sauce bubbles enthusiastically and cook, stirring occasionally, until the tomatoes thicken and you can smash the garlic a bit, 5 to 10 minutes. Taste, adjust the seasoning, and adjust the heat so the sauce stays hot but doesn’t boil.
Add the pasta to the boiling water, and cook, stirring occasionally, for 5 minutes, then start tasting. When the pasta is tender but still has some bite, scoop out 2 cups cooking water, then drain the pasta and return it to the pot.
Add the sauce and cheese to the pasta; swirl 1/2 cup cooking water in the skillet to loosen every last drop of sauce and add that to the pot too. Toss with tongs to coat the noodles, adding more cooking water or butter, a little at a time, to make the pasta creamy. Taste and adjust the seasoning and serve, passing more cheese at the table.