Cook your diced bacon in a large skillet on medium high heat. Fry the bacon a bit until slightly crispy. You want a little bit of crispiness but don't overdo this part. :-) This may take between 3-5 minutes. Stir often.
Once the bacon is slightly crispy, remove all but about 2-3 tablespoons of the bacon fat. Add the garlic, and then stir fry continuously for around 2 minutes. Set aside.
Place eggs and parmesan cheese in a small bowl. Whisk well until both ingredients are well incorporated. Set aside.
Meanwhile, cook your penne according to package directions. Just prior to draining, reserve a cup of the pasta water. Drain penne.
Add the penne to the skillet which has the garlic and bacon. Allow this to cool about a minute, and then add the whisked egg and parmesan cheese to the skillet. Stir well to incorporate, and add a little reserved pasta water (only if needed) to loosen up the pasta. You are aiming for a smooth and silky sauce, with no scrambled eggs in sight. :-) Season with salt and pepper to taste.
Serve! Garnish with Italian parsley, black pepper, and additional parmesan cheese if desired. Mangia!