Cut off the rind and the pepper layer. Then, cut the guanciale into 1 cm (0.4”) slices, stack them, and cut into 1 cm (0.4”) cubes.

To a large bowl, add the egg yolks, the freshly ground pepper, the Grana Padano, and the pecorino Romano. Mix with a whisk until well blended.

Add the guanciale to a heated cast iron pan (no oil, butter, or fat added), then sauté over high heat, tossing the guanciale as you do, making sure it browns on all sides. Once the guanciale starts to smoke and fry, lower the heat so it does not burn. Let it cook in its fat until crispy on the outside and soft on the inside.

When the guanciale is done, drain the rendered fat into a heatproof bowl, and let both the fat and the guanciale cool to room temperature.

Cook the spaghetti according to package directions — they should be just shy of al dente when done as they will continue to cook with the sauce later.

Add some of the rendered fat from the guanciale to the bowl with egg yolks and mix. Then, transfer the spaghetti into the bowl, add a ladle of pasta water to the bowl, place the said bowl over a water bath, and constantly stir until the sauce thickens.

Remove from the water bath and add the guanciale and toss to combine.

Transfer to warmed plates, taking care each portion has equal amounts of guanciale. Then, sprinkle each portion of carbonara with freshly ground pepper and pecorino Romano. Serve immediately, or the sauce will dry out and become sticky.