Dice your guanciale into small pieces and place it in a cold skillet. Turn the heat to medium-low and cook for about 10-15 minutes until crispy.

Use a slotted spoon to remove the crispy guanciale and set it aside on a plate lined with paper towels.

If using garlic, increase the heat slightly, add minced garlic to the pan, and sauté for about 30 seconds.

In a mixing bowl, whisk together fresh eggs, grated Pecorino Romano cheese, grated Parmesan, and black pepper until smooth.

Bring a large pot of salted water to a boil, add spaghetti, and cook according to package instructions (8-10 minutes) until al dente. Reserve a cup of pasta water, then drain.

Add the drained spaghetti to the skillet with the reserved guanciale fat, toss over low heat to soak up the fat.

Off the heat, pour the egg and cheese mixture onto the hot pasta, tossing continuously to create a creamy coating.

If the sauce is too thick, add reserved pasta water gradually until desired consistency is reached.

Fold the crispy guanciale back into the pasta and reserve some for garnish.

Plate immediately, garnishing with reserved guanciale and extra cheese and black pepper. Serve hot.