Dice the guanciale into ¼-inch pieces and render in a cold skillet over medium-low heat for about 10-15 minutes until crispy.

Remove the crispy guanciale and place on paper towels to absorb excess grease, leaving the rendered fat in the skillet.

Sauté minced garlic in the rendered fat for 1-2 minutes until fragrant, if using.

Whisk together the eggs, grated Pecorino Romano, and black pepper in a mixing bowl until combined.

Boil salted water and cook spaghetti until al dente, about 8-10 minutes, reserving a cup of pasta water before draining.

Combine drained spaghetti with the rendered guanciale fat, tossing to absorb flavors.

Remove from heat and pour the egg mixture over the hot pasta, tossing vigorously to coat.

Adjust sauce consistency with reserved pasta water as needed.

Fold the crispy guanciale back into the pasta and toss thoroughly.

Season with salt and black pepper to taste, serve immediately garnished with extra guanciale and cheese.