Cook the guanciale in a skillet until crispy, then set aside.

In a bowl, whisk together the eggs and cheese. Thin the mixture with a little water or milk if needed.

In the rendered guanciale fat, cook the spaghetti with about 2 cups (500 ml) of water.

Once the pasta is cooked, let it cool until the temperature drops below 150°F (65°C) to avoid scrambling the eggs. Mix the pasta with the egg and cheese mixture, adding more water if needed, but do not exceed 150°F (65°C). Serve topped with the crispy guanciale.