Read through the instructions before beginning this recipe.
Beat the eggs, parmesan, and 1/4 teaspoon black pepper together in a bowl until fully combined.
Bring a large pot of water to a boil. Add 1 teaspoon kosher salt and the dry spaghetti. Cook the pasta according to package instructions. It is important that while the pasta is cooking you work on the sauce so it is ready when the pasta is done and still hot. Be sure to reserve 1/2 cup of the pasta water when you drain it.
While the pasta is cooking, cook the bacon until almost crisp in a large skillet. Add the garlic and sauté for 30 seconds, until just fragrant. (If the pasta isn't done yet, remove from heat, making sure the garlic does not burn.)
Add the drained hot pasta to the bacon and garlic and toss over the heat to combine for about 2 minutes, ensuring that the spaghetti gets well coated in the rendered bacon fat.
Remove the pan from the heat and mix in the egg mixture. It will thicken and coat the pasta. (It is important to remove the pan from the heat. If you leave it over heat when you add the egg-cheese mixture, it will scramble the eggs.) If the sauce becomes too thick, you can add a little of the reserved pasta water.
Plate the hot pasta, and top freshly ground black pepper, additional parmesan, and freshly chopped parsley.