Prepare the Pasta Water: Fill a large pot with water and bring it to a vigorous boil. Add about 1 tablespoon of kosher salt per every 2 quarts of water. This ensures your pasta is seasoned properly as it cooks.
Crisp the Pancetta or Bacon: While waiting for the water to boil, heat the olive oil or butter in a large sauté pan over medium heat. Add the diced pancetta or bacon and cook slowly, stirring occasionally, until the meat is golden brown and crisp. This slow rendering process releases rich flavors and fat.
Add Garlic for Extra Aroma (Optional): If you enjoy garlic, stir in the minced cloves and sauté for another minute, letting their aroma infuse the fat. Once fragrant, remove the pan from heat to prevent burning and transfer the pancetta and garlic mixture to a large mixing bowl.
Whisk Eggs and Cheese: In a separate bowl, beat together the whole eggs with half of the grated cheese until smooth and creamy. This mixture will form the base of your sauce.
Cook the Pasta to Al Dente: Add the spaghetti to the boiling salted water and cook uncovered until al dente — firm to the bite but cooked through — following package instructions closely. Remember to reserve a cup of the pasta cooking water before draining.
Combine Pasta with Pancetta: Using tongs, swiftly transfer the hot pasta from the pot directly into the bowl containing the crispy pancetta and garlic. Make sure the pasta is wet with some cooking water to help bind the sauce.
Create the Creamy Carbonara Sauce: Quickly pour the egg and cheese mixture over the pasta and toss vigorously. The residual heat from the pasta will gently cook the eggs, creating a silky, creamy coating without scrambling them.If the sauce seems thick, add reserved pasta water little by little until you achieve a smooth consistency. Season and Serve Immediately: Season the carbonara with freshly ground black pepper and salt to taste. Sprinkle the remaining grated cheese over the top and, if desired, garnish with freshly chopped parsley. Serve immediately to enjoy the dish at its creamy best.