Cut the guanciale into 0.5 cm thick batons. Heat a large non-stick pan over medium-high heat and add the guanciale. Sauté for about 4-5 minutes until golden and crisp.

In a mixing bowl, crack 2 large eggs and separate 2 yolks. Whisk together and gradually mix in grated Parmigiano Reggiano and black pepper until creamy.

Bring 4 liters of salted water to a boil in a large pot, add spaghetti, and cook according to package instructions until al dente.

Before draining spaghetti, reserve about a cup of starchy pasta cooking water.

Drain spaghetti and add it to the pan with guanciale. Toss gently in the rendered fat for about 30 seconds.

Transfer hot spaghetti to the egg and cheese mixture. Quickly add a splash of reserved pasta water while mixing vigorously until creamy.

Serve immediately in warm bowls, garnishing with extra grated Parmigiano Reggiano and black pepper.