Bring a large pot of salted water to a boil and cook spaghetti according to package instructions until al dente. Reserve 1 cup of pasta water, then drain.
In a bowl, whisk together eggs and Parmesan cheese until well combined. Set aside.
In a large skillet over medium heat, cook diced pancetta until crispy. Add minced garlic and sauté for 30 seconds.
Remove the skillet from heat. Quickly add the drained spaghetti, tossing to coat in the pancetta fat.
Slowly pour in the egg and cheese mixture while continuously tossing to create a creamy sauce. Add reserved pasta water as needed for desired consistency.
Season with salt and freshly ground black pepper to taste.
Garnish with fresh parsley, if desired. Serve immediately.