Preparation: Bring a large pot of salted water to a boil. Cook the spaghetti according to the package instructions until al dente. Reserve 1 cup of pasta water, then drain the spaghetti and set aside.
Cook Pancetta and Garlic: In a large skillet, heat olive oil over medium heat. Add the diced pancetta or guanciale and cook until crispy and golden brown, about 5-6 minutes. Add the minced garlic and cook for an additional 1-2 minutes until fragrant.
Prepare Sauce: In a separate bowl, whisk together the eggs, grated Parmesan cheese, and a generous amount of freshly ground black pepper.
Combine Pasta and Sauce: Add the cooked spaghetti to the skillet with the pancetta and garlic. Toss well to combine, ensuring that the spaghetti is coated evenly with the rendered fat.
Add Sauce Mixture: Remove the skillet from heat. Pour the egg and Parmesan mixture over the spaghetti, stirring quickly and continuously to coat the pasta and create a creamy sauce. If the sauce is too thick, gradually add the reserved pasta water a little at a time until desired consistency is reached.
Serve: Transfer the spaghetti carbonara to serving plates. Garnish with additional grated Parmesan cheese, freshly ground black pepper, and chopped parsley. Serve immediately, and enjoy the comforting flavors of Italy!