Bring a pot of salted water to a boil and cook the whole wheat spaghetti according to package directions until al dente.
While pasta cooks, dice the pancetta and place it in a large skillet over medium heat, sautéing until golden and crispy.
Remove the pancetta with a slotted spoon, leaving the rendered fat in the pan, and add the diced chicken breast seasoned with sea salt.
Sauté the chicken until cooked through and golden, adding the minced garlic during the last minute of cooking.
In a small bowl, whisk together the egg, grated parmesan cheese, and black pepper until well combined.
Reserve 0.25 cup of pasta water, then drain the spaghetti and add it to the skillet with the chicken and baby spinach.
Remove the skillet from the heat immediately and pour in the egg mixture, tossing vigorously to create a creamy sauce without scrambling the eggs.
Thin the sauce with a splash of reserved pasta water if needed, top with crispy pancetta, and serve immediately.