Bring a pot of water to boil. When it's boiling, add salt. Throw the pasta in and cook until it's before al dente (Cook for about half the indicated time on the package)– this is important because the pasta will finish cooking in the sauce. Be sure to reserve some pasta water.
Just before the pasta boils and you throw the pasta into the water, throw the guanciale into a large cold pan that will also fit the pasta.
Turn the heat up to medium and let the guanciale cook until crispy - about 10-15 minutes. Remove from the pan, but keep the rendered fat in. If the pasta isn't ready by this time, remove from the burner.
Add the al dente pasta to the pan (still over medium heat) with the rendered guanciale fat. Add a ladle of pasta water as well.
While the pasta is finishing in the pan, place the grated pecorino in a bowl, and add a bit of pasta water to it. Mix with a fork until a paste forms.
Let the pasta cook for a few minutes until cooked to desired consistency (al dente), so it releases its starches and a creamy consistency starts to form when mixed with the guanciale fat. Add more pasta water if needed. There should be a little bit of liquid left at the bottom of the pan, it shouldn't be completely dry. Remove the pan from the heat.
Add the pecorino paste to the pasta. Mix with a wooden spoon.
If the pecorino cream needs to be thinned out a bit more, add more pasta water. Add the ground black pepper.
Add the gunaciale and mix again until evenly distributed in the pasta.
Plate, top with additional black pepper and grated pecorino if desired. Enjoy!