Bring a large pot of water to a boil over medium heat and add a large pinch of kosher salt.
Add the pasta and cook according to package instructions to al dente. Use a measuring cup or bowl to remove about ¼ cup of starchy pasta water and set aside.
While the pasta is cooking, add cubed butter to a large mixing bowl.
Once the pasta is cooked, turn off the heat and use tongs to remove it from the pot and add the hot pasta directly to the mixing bowl with butter. Immediately begin stirring the pasta in with the butter as quickly as you can.
While stirring, sprinkle in about ⅓ of the parmesan cheese with a splash of the reserved starchy pasta cooking water and continue stirring. Repeat this process until all of the cheese has been incorporated and the butter is fully emulsified.
You do not have to use all of the pasta water.
Taste the pasta and add salt as desired, though you may not need much. You may also add in some cracked black pepper at this point.
Serve pasta hot and use a spoon to drizzle on any extra alfredo sauce. You may wish to garnish with parsley or chives.