Set up a sous vide water bath and bring up to 145 degrees F (63 C).

If using guanciale, trim off the tough outer skin. Cut the meat into ½-inch cubes and place in a large skillet over medium heat. If using pancetta, add a pinch of salt and pepper into the pan. Sauté for 4-6 minutes, or until deeply browned and crispy. Turn off the heat.

In a ziplock or vacuum-sealed bag, add the egg yolks, grated cheese, and two spoonfuls of the liquid guanciale fat from the pan. Squeeze the bag to lightly mix the ingredients, then press all the air out and seal it up. Place in the sous vide bath and cook for one hour.

As the eggs near completion, bring a large pot of water to boil and salt it. Add the pasta and cook as directed.

After one hour of cooking, drain the egg mixture into a bowl and whisk it vigorously until very smooth.

Drain the cooked pasta and transfer into a large mixing bowl. Add the egg mixture and stir all together. Finally, add the guanciale and a generous sprinkle of black pepper. Mix again, and serve immediately.