Bring a large pot of water to a vigorous boil. Once boiling, add a pinch of salt and the spaghetti, stirring occasionally. Cook the pasta until just slightly beyond al dente. In a small to medium bowl, whisk together the egg yolks, grated Pecorino, and black pepper until smooth and well combined. Just before using, stir in ⅓ to ½ cup (80–120 ml) of hot pasta water to loosen the mixture. Slice the guanciale into short, thin strips. In a large skillet, heat the olive oil over medium heat and cook the guanciale until it reaches your preferred level of crispiness—some prefer it crunchy, while others like it a bit softer. Remove the guanciale with a slotted spoon onto a clean plate, but leave the rendered fat in the pan. Over medium-high heat, add the cooked pasta to the pan along with another ⅓ to ½ cup (80–120 ml) of hot pasta water and toss to combine. Remove the pan from the heat and quickly pour in the egg mixture, stirring vigorously to coat the pasta evenly. Add an additional ⅓ to ½ cup of hot (not boiling) pasta water as needed, tossing continuously until the sauce becomes creamy and smooth. Finally, fold in the crispy guanciale gently. Serve immediately, topped with extra freshly grated Pecorino and a generous crack of black pepper. Enjoy!