Bring a large pot of salted water to a boil. Add spaghetti and cook according to package instructions until al dente.

In a skillet, cook the pancetta over medium heat until crispy. Remove from heat.

In a mixing bowl, whisk together eggs, Parmesan, Pecorino, and black pepper until well combined.

Once the pasta is cooked, reserve a cup of pasta water and drain the rest. Quickly add the hot pasta to the skillet with pancetta.

Remove from heat and immediately pour the egg mixture over the pasta, tossing quickly to create a creamy sauce, adding reserved pasta water as needed to reach desired consistency.

Serve immediately, garnished with additional cheese and chopped parsley if desired.