Bring a large pot of salted water to boil. Add spaghetti and cook until al dente (about 9–10 minutes). Reserve 1 cup of pasta water before draining.

While pasta cooks, heat a skillet over medium heat. Add diced guanciale and cook until crispy and golden (5–7 minutes). Remove pan from heat.

In a mixing bowl, whisk together eggs, egg yolk, Pecorino Romano, and black pepper until smooth.

Once pasta is cooked, transfer it into the skillet with guanciale (do not add egg mixture yet). Toss well to coat pasta in the rendered fat.

Remove skillet from heat completely (important to avoid scrambling eggs). Quickly pour egg-cheese mixture over pasta.

Toss vigorously using tongs, adding reserved hot pasta water gradually until sauce becomes creamy and coats every strand.

Adjust consistency—sauce should be glossy and silky, not runny.

Taste and add more Pecorino or pepper if desired.

Serve immediately in warm bowls.

Garnish with extra Pecorino and freshly cracked black pepper.