Fill a large pot with lightly salted water and bring to a rolling boil. Stir in spaghetti and cook, stirring occasionally, until al dente (about 12 minutes). Reserve 1 cup pasta water, then drain.

Warm a skillet over medium heat. Add diced guanciale and cook until golden and crispy, about 5–7 minutes. Remove from heat.

In a bowl, whisk together eggs, egg yolks, and grated Pecorino Romano until smooth and creamy.

Add drained spaghetti to the skillet with guanciale off the heat and toss to coat in rendered fat.

Pour egg–cheese mixture over spaghetti, quickly tossing to create a silky sauce. Add reserved pasta water a splash at a time until desired creaminess.

Season generously with freshly ground black pepper and sprinkle extra Pecorino Romano on top before serving.