Steps
1. Bring a pot of salted water to a boil and cook the spaghetti according to package instructions until al dente.
2. In a pan over medium heat, cook the pancetta or guanciale until crispy. Remove from heat.
3. In a bowl, whisk together the egg, grated Pecorino Romano, salt, and black pepper.
4. Once the pasta is cooked, reserve a cup of pasta water and drain the rest.
5. Quickly add the hot pasta to the pan with pancetta, tossing to combine.
6. Remove from heat and add the egg mixture, stirring rapidly to create a creamy sauce. If too thick, add reserved pasta water a little at a time.
7. Serve immediately, garnished with extra cheese and a sprinkle of black pepper.