Bring a pot of salted water to a boil and cook the whole wheat spaghetti until al dente, reserving 1/4 cup of the starchy pasta water.
While pasta cooks, heat a large skillet over medium heat and sauté the diced pancetta until the fat renders and it becomes crispy.
Add the diced chicken breast to the skillet with the pancetta and cook until golden brown and cooked through, about 5-6 minutes.
Stir in the minced garlic and baby spinach, sautéing just until the spinach is wilted and the garlic is fragrant.
In a small bowl, whisk together the whole egg, egg yolk, grated parmesan, and cracked black pepper until smooth.
Turn off the heat on the skillet and add the cooked pasta, tossing it with the chicken and pancetta mixture.
Slowly pour the egg mixture over the pasta while tossing constantly, adding a splash of reserved pasta water as needed to create a creamy, glossy sauce without scrambling the eggs.
Season with sea salt to taste and serve immediately while the sauce is warm and velvety.