Boil the whole wheat spaghetti in salted water until al dente, reserving 0.25 cup of the starchy pasta water before draining.
In a large skillet over medium heat, sauté the diced pancetta until the fat renders and it becomes golden and crispy.
Add the diced chicken breast and minced garlic to the skillet, cooking until the chicken is browned and no longer pink inside.
While the chicken cooks, whisk together the whole egg, liquid egg whites, and grated parmesan in a small bowl until smooth.
Stir the fresh spinach into the skillet with the chicken and pancetta, allowing it to wilt for about 30 seconds.
Turn off the heat completely and add the cooked pasta to the skillet, tossing it with the meat and spinach.
Quickly pour the egg mixture and the reserved pasta water over the noodles, stirring constantly for 1 minute to create a creamy, silky sauce without scrambling the eggs.
Season the dish with sea salt and a generous amount of cracked black pepper before serving immediately.