Begin by bringing a large pot of generously salted water to a boil for the pasta.

While the water heats, cook the guanciale in a large, cold skillet over medium heat. Render the fat until the pieces are crispy and golden, about 8-10 minutes. Remove from heat and set aside, leaving the rendered fat in the pan.

In a medium bowl, whisk together the 3 egg yolks, 1 whole egg, grated Pecorino Romano, and a generous amount of freshly cracked black pepper until a thick, smooth paste forms.

Cook the spaghetti in the boiling water according to package instructions for al dente. Just before draining, reserve about 1 cup of the starchy pasta cooking water.

Working quickly, drain the pasta and immediately add it to the skillet with the guanciale and its fat. Toss over low heat for one minute to coat the pasta and warm the pan.

Remove the skillet from the heat. Pour the egg and cheese mixture into the hot pasta, tossing rapidly with tongs. The residual heat will cook the eggs into a creamy sauce.

Add reserved pasta water, a few tablespoons at a time, until you achieve a luxuriously silky, creamy consistency that coats each strand.

Serve immediately with an extra sprinkle of Pecorino and a final crack of black pepper.