01 - Bring a large pot of salted water to a boil. Cook the spaghetti or fettuccine until al dente following package instructions. Reserve ½ cup pasta water, then drain.
02 - Heat olive oil in a large skillet over medium heat. Add beef bacon strips and sauté until crispy and golden, approximately 5–7 minutes. Remove from heat and leave bacon and rendered fat in the pan.
03 - Whisk together egg yolks, whole egg, heavy cream, Parmesan cheese, black pepper, and sea salt in a bowl until smooth.
04 - Add the drained pasta to the skillet with the beef bacon. Toss thoroughly to coat the pasta evenly with the bacon fat.
05 - Remove skillet from heat. Immediately pour the egg and cream mixture over the pasta, tossing quickly to avoid curdling. Gradually add reserved pasta water, tossing until a creamy sauce forms that clings to the pasta.
06 - Plate the pasta and garnish with additional Parmesan cheese and chopped fresh parsley if desired. Serve immediately.