Dice the guanciale into small cubes and place in a cold skillet. Heat over medium-low heat for 10-15 minutes until golden brown and crispy. Remove from skillet, leaving fat.

If using, sauté minced garlic in reserved fat over low heat for 30 seconds until fragrant, being careful not to burn it.

In a bowl, whisk together the eggs, Pecorino Romano, and Parmesan cheese with freshly cracked black pepper until smooth and creamy.

Boil salted water in a large pot, add spaghetti, and cook for 8-10 minutes until al dente. Reserve 1 cup of pasta water before draining.

Add drained spaghetti to the skillet with guanciale fat (and garlic if used) off the heat. Pour in the egg and cheese mixture, tossing to create a creamy sauce.

Gradually add reserved pasta water to adjust consistency, stirring until smooth and silky.

Fold in crispy guanciale and serve immediately, garnished with extra cheese and black pepper.