This recipe is in Fabio Trabocchi's fantastic cookbook Cucina of Le Marche, which I highly recommend! It's super easy to make, and if you don't have guanciale you can substitute pancetta.

Bring a large pot of salted water to a rolling boil.
Meanwhile, remove any herbs and spices from the surface of the guanciale and trim away any dry spots. Cut into medium-fine dice.
If using pancetta, cut it into medium-fine dice.
Put the guanciale or pancetta in a large sauté pan, place the pan over medium-high heat, and slowly render the fat from the meat.
When the guanciale begins to crisp, remove the pan from the heat and set aside.
Add the bucatini to the boiling water and cook until al dente, 8 to 10 minutes.
Meanwhile, return the pan with the guanciale to the stovetop and slowly warm over medium-low heat.
Drain the pasta, reserving about ¼ cup of the cooking liquid. Add the pasta and grated cheese to the guanciale and shake the pan back and forth to combine the ingredients. Add just enough of the reserved pasta water - a few tablespoons should suffice - to create a sauce with a creamy consistency. Season with salt and pepper to taste and serve immediately in warm pasta bowls.
Buon appetito!
Ingredients
Directions
Bring a large pot of salted water to a rolling boil.
Meanwhile, remove any herbs and spices from the surface of the guanciale and trim away any dry spots. Cut into medium-fine dice.
If using pancetta, cut it into medium-fine dice.
Put the guanciale or pancetta in a large sauté pan, place the pan over medium-high heat, and slowly render the fat from the meat.
When the guanciale begins to crisp, remove the pan from the heat and set aside.
Add the bucatini to the boiling water and cook until al dente, 8 to 10 minutes.
Meanwhile, return the pan with the guanciale to the stovetop and slowly warm over medium-low heat.
Drain the pasta, reserving about ¼ cup of the cooking liquid. Add the pasta and grated cheese to the guanciale and shake the pan back and forth to combine the ingredients. Add just enough of the reserved pasta water - a few tablespoons should suffice - to create a sauce with a creamy consistency. Season with salt and pepper to taste and serve immediately in warm pasta bowls.
Buon appetito!