Freeze the guanciale for 15 minutes to make it easier to cut. Then slice into 1/4-inch pieces.
Cook the guanciale in a large skillet over medium heat until it is golden and crispy, about 10 minutes. Remove guanciale and set aside, leaving the fat in the skillet.
Bring a large pot of water to a boil. Add a pinch of salt and the pasta, cooking until al dente.
While the pasta cooks, add black pepper to the skillet with the guanciale fat and heat over medium heat.
Transfer the cooked pasta directly from the pot to the skillet using tongs, reserving some pasta water.
Toss the pasta in the skillet with the guanciale fat and black pepper, adding reserved pasta water a little at a time until the sauce coats the pasta.
Remove from heat, add the guanciale back to the skillet along with the Pecorino Romano cheese. Toss until the cheese melts and the sauce becomes creamy.
Serve immediately, topped with additional Pecorino Romano cheese.