Cook the Pasta: In a large pot of salted boiling water, cook the fettuccine according to package instructions until al dente. Reserve 1 cup of pasta water, then drain the pasta.
Prepare the Sauce: In a bowl, whisk together the eggs and Pecorino Romano cheese until smooth. Set aside.
Cook the Pancetta: In a large skillet over medium heat, add the diced pancetta. Sauté until crispy and golden, about 5-7 minutes. Add the minced garlic and cook for an additional minute until fragrant.
Combine Pasta and Sauce: Add the drained fettuccine to the skillet with pancetta, tossing to combine. Remove the skillet from heat, then quickly pour the egg and cheese mixture over the pasta, using tongs to toss continuously. The residual heat will cook the eggs gently and create a creamy sauce. If the sauce is too thick, add reserved pasta water a little at a time until desired consistency is reached.
Serve: Season with salt and freshly cracked black pepper to taste. Garnish with chopped parsley and extra Pecorino Romano cheese if desired.