Cook spaghetti according to package directions, reserving ¼ cup pasta water.
As the spaghetti cooks, brown bacon in a pan. Once crisp, remove the pan from heat.
In a bowl, whisk together eggs, parmesan and salt and pepper.
Once the spaghetti is ready, pour the reserved pasta water into the pan with the bacon. Drain spaghetti and add it to the pan.
On very low heat, pour in egg mixture and immediately and very quickly mix together and remove from the heat. You want to make a creamy and smooth sauce without overcooking / scrambling the eggs.