We saw this video of "The King of Carbonara" in Rome and new we had to try it: the technique of using the fat from the Guanciale and gently cooking the sauce in a bain-marie appealed to us.
We first had Bucatini alla Carbonara at A. V. Restaurante Italiano (RIP) in Washington DC years ago; it is one of our "go to" dishes at home when we want some easy comfort food. Irene and I have slightly different approaches: she adds the hot pasta to the sauce and relies on the retained heat to cook the sauce, while I find that a bit too raw and add a bit of heat when combining in a pan. Either way, it's fast and satisfying: you can prep the sauce in the time it takes the pasta to cook.
With another practice or two, I should be able to prep the sauce while the pasta cooks for chef Chef Monosilio's more careful technique. In the video, he cuts a large slab of Guanciale into cubes, fries them to render the fat and crisp the meat, and uses some of that fat in the sauce -- that's what hooked us. We can readily find 100 g packages of sliced Guanciale here in Barcelona: it's not cubed, but sliced like thick American bacon; it does have a good piggy funk to it. He uses a mix of Pecorino and Grana Padano because he said that folks now don't like the high salt level of Pecorino; the version of that cheese we get here isn't as dry and salty as what we found in the States, but we'll use his mix. The proportions below are for two, and it's quite rich; here, I'm backing out the cheese a bit from my first attempt which was just too much.