Bring a pot of salted water to a boil and cook the spaghetti until al dente according to package instructions. Reserve 1/2 cup of pasta water, then drain.
In a bowl, whisk together the eggs, grated Pecorino Romano cheese, and black pepper until well combined.
In a pan over medium heat, cook the pancetta or bacon until crispy. Remove from heat.
Add the cooked spaghetti to the pan with pancetta and toss to combine.
Pour the egg and cheese mixture over the pasta and quickly toss to create a creamy sauce. Add a splash of reserved pasta water if needed for consistency.
Serve immediately with extra cheese and black pepper on top.
