Bring a large pot of water to a boil and season with the sea salt.
Add the spaghetti and cook until al dente, usually about 8 to 10 minutes.
While the pasta cooks, sauté the diced pancetta in a skillet over medium heat until it becomes crispy and golden.
In a medium bowl, whisk together the whole eggs, egg whites, Parmesan, and Pecorino Romano until smooth.
Reserve 0.5 cup of the starchy pasta water before draining the spaghetti.
Add the hot spaghetti directly into the skillet with the pancetta and toss to coat in the flavorful fat.
Remove the skillet from the heat and quickly pour in the egg and cheese mixture, whisking constantly to create a creamy sauce.
Slowly add the reserved pasta water a tablespoon at a time, tossing until the sauce is silky and clings to the noodles.
Season with the black pepper and serve immediately while hot.