Bring a large pot of salted water to a boil and cook the whole wheat spaghetti until al dente according to package directions.
While the pasta cooks, dice the pancetta into small cubes and sauté in a large skillet over medium heat until crispy and the fat has rendered.
In a medium mixing bowl, whisk together the whole egg, egg whites, grated parmesan cheese, and black pepper until the mixture is uniform and frothy.
Reserve approximately 0.25 cup of the starchy pasta cooking water, then drain the spaghetti thoroughly.
Turn off the heat on the skillet containing the pancetta and immediately add the hot pasta, tossing it to coat every strand in the savory rendered fat.
Slowly pour the egg and cheese mixture over the pasta while continuously tossing with tongs to create a creamy, emulsified sauce without scrambling the eggs.
Gradually add the reserved pasta water one tablespoon at a time until the sauce reaches a silky, glossy consistency.
Garnish with fresh chopped parsley and serve immediately while the sauce is warm and velvety.