Step 1

Bring a large pot of water to a boil, then salt generously with kosher salt. Cook the fettuccine, stirring often during the first 4 minutes and occasionally after that, according to package directions, until al dente.

Step 2

Drain the pasta, reserving 1 cup of pasta water (or more to reheat the pasta later, if you predict you will have leftovers).

Step 3

Return the pasta to the pot, off heat, and stir in the sliced butter, a small pinch of salt, half the cheese and a splash of the reserved pasta water (about ¼ cup). Toss the pasta vigorously, adding the rest of the cheese and more pasta water as needed for the sauce to emulsify. If you are having trouble getting the cheese to melt quickly, it's okay to turn the heat on low under the pot. Just work quickly so the sauce doesn't curdle.

Step 4

Serve on warmed plates (see notes) with more parmesan cheese and a fresh grinding of black pepper.