Boil the pasta Start by bringing a large pot of salted water to a boil. Add the spaghetti and cook according to the package instructions until al dente. Before draining, scoop out about half a cup of the pasta water and set it aside—you’ll need it for the sauce.
Cook the pancetta While the pasta is cooking, heat olive oil in a large skillet over medium heat. Add the diced pancetta and cook until it becomes crispy and golden. Stir in the minced garlic and let it cook for about 1 minute, just until fragrant. Then, remove the pan from heat.
Make the creamy base In a mixing bowl, whisk together the eggs, egg yolk, and grated Parmesan cheese. Add a pinch of salt and freshly ground black pepper. This will be your rich and creamy base.
Combine everything (off the heat!) Once the pasta is cooked and drained (don’t forget to save the pasta water), add it to the skillet with the pancetta and garlic. Make sure the skillet is no longer on direct heat—this prevents the eggs from scrambling.
Create the silky sauce Quickly pour the egg and cheese mixture over the hot pasta and toss everything together using tongs or a pasta fork. Add a little reserved pasta water, a tablespoon at a time, until the sauce reaches a silky, creamy consistency.
Finish and serve Taste and adjust the seasoning if needed. Serve immediately while warm and creamy. Sprinkle with extra Parmesan cheese, freshly ground black pepper, and a bit of chopped parsley if desired.