1Bring a large pot of salted water to a boil. Add the spaghetti and cook until al dente, about 8-10 minutes.
While the pasta is cooking, heat a large skillet over medium heat. Add the pancetta and cook until crispy, about 5-7 minutes. Add the garlic and cook for another minute. Remove from heat.
In a medium bowl, whisk together the eggs, pecorino cheese, and parmesan cheese. Season with a pinch of salt and a generous amount of black pepper.
Drain the spaghetti, reserving about 1 cup of the pasta water. Add the spaghetti to the skillet with the pancetta and garlic. Toss to combine.
Remove the skillet from the heat and quickly pour in the egg and cheese mixture, tossing constantly to create a creamy sauce. If the sauce is too thick, add a little reserved pasta water until you reach the desired consistency.
Serve immediately, garnished with additional pecorino cheese and black pepper if desired.