Bring a large pot of water to a rolling boil and season generously with sea salt.
Add the whole wheat spaghetti and cook until al dente, usually about 8 to 10 minutes.
While the pasta boils, place the diced pancetta in a cold medium skillet and set the heat to medium-low.
Slowly render the fat from the pancetta until the pieces become golden brown and crispy, then remove from heat.
In a small mixing bowl, whisk together the whole egg, liquid egg whites, and grated parmesan cheese until the mixture is smooth and pale.
Reserve exactly 0.25 cup of the starchy pasta water before draining the spaghetti.
Return the skillet with pancetta to low heat, add the drained pasta and baby spinach, and toss until the spinach just begins to wilt.
Turn off the heat completely and quickly pour in the egg and cheese mixture, stirring constantly and adding the reserved pasta water to create a creamy, emulsified sauce.
Finish with freshly cracked black pepper and serve immediately in a warm bowl.