1. Bring a large pot of salted water to a boil and cook the pasta until al dente. Reserve 1 cup of pasta water before draining.
2. In a bowl, whisk together eggs, Parmesan cheese, salt, and pepper until well combined. This mixture should be smooth and creamy.
3. In a large pan, melt butter over medium heat. If using, add minced garlic and pancetta, cooking until the garlic is fragrant and pancetta is crispy.
4. Reduce the heat to low and add cooked pasta to the pan. Gradually pour the egg mixture over the pasta, tossing continuously to coat each strand evenly.
5. Slowly add reserved pasta water, a little at a time, until the sauce reaches your desired consistency. This step is crucial to prevent the eggs from scrambling.
6. Serve immediately, garnished with freshly chopped parsley if desired.

Mama Lou always said the key to a perfect pasta recipe egg is patience. Stir gently and allow the heat of the pasta to cook the eggs slowly, creating that luscious, creamy sauce.