1/2 teaspoon crushed red pepper flakes, plus more for serving
4 garlic cloves, thinly sliced
Handful basil sprigs, plus more for serving
Kosher salt and freshly ground black pepper
1 pound spaghetti
Cut a thin slice off the base of each tomato. Hold tomato at stem end and use large holes of a box grater to grate flesh and pulp into a large bowl. The skin should unfurl as you go, until you’re left with just the stem and shredded skin in your hand (which you can discard). Some skin might pass through the grater, and that’s fine.
In a large skillet, combine olive oil, pepper flakes, garlic, and basil sprigs. Place over medium heat and cook, stirring occasionally, until garlic is translucent and very fragrant, about 2 minutes. Add grated tomato and season with salt and black pepper. Simmer until sauce is slightly thickened, about 10 minutes, then remove from heat. Pluck out basil sprigs and discard.
Meanwhile, bring a large pot of generously salted water to a boil. Add pasta and cook, stirring occasionally, until spaghetti is al dente according to package instructions. Scoop out about 1 cup of pasta cooking liquid, then drain spaghetti. Add pasta to skillet with tomato sauce and place over medium heat. Cook, gently tossing, until sauce is hot and pasta is well dressed. Adjust as needed with reserved pasta water.
Serve spaghetti and tomato sauce with some pepper flakes sprinkled over and topped with some torn basil leaves.