Cook spaghetti in a large pot of salted boiling water until al dente. Drain and reserve 1/2 cup of pasta water.
In a skillet, cook pancetta or bacon until crispy. Add minced garlic and cook for an additional minute.
In a bowl, whisk together eggs, grated Parmesan cheese, salt, and black pepper.
Add cooked spaghetti to the skillet with pancetta and garlic. Remove from heat and quickly toss with egg mixture. The residual heat will cook the eggs without scrambling them.
If the pasta seems too dry, add some reserved pasta water to loosen it up.
Garnish with chopped parsley and extra grated Parmesan cheese. Serve immediately.
