Bring a large pot of salted water to a boil. Add the pasta and cook as the label directs. Reserve 1/4 cup cooking water, then drain the pasta.
Meanwhile, cook the bacon in a large skillet over medium heat, stirring occasionally, until crisp, about 8 minutes. Add the spaghetti and reserved pasta cooking water to the skillet and toss to combine.
Add the eggs, parmesan, 1/2 teaspoon salt and 1 1/2 teaspoons pepper; toss to coat. Cook, tossing continuously to avoid scrambling the eggs, until the sauce is creamy, about 1 minute. Stir in the parsley. Serve topped with more parmesan.