Bring a large pot of salted water to a boil and cook the whole wheat spaghetti according to package directions until al dente.
While the pasta cooks, dice the chicken breast into small bite-sized pieces and mince the garlic.
In a large skillet over medium heat, add the pancetta and cook until the fat renders and the meat becomes crispy.
Add the olive oil and diced chicken to the skillet with the pancetta; sauté until the chicken is golden and cooked through.
Add the minced garlic to the skillet and cook for 30 seconds until fragrant, then turn the heat to the lowest setting.
In a small bowl, whisk together the egg, grated parmesan cheese, and black pepper until well combined.
Reserve 0.25 cup of the pasta cooking water, then drain the spaghetti.
Add the hot pasta directly to the skillet with the chicken and pancetta, tossing to combine.
Remove the skillet from the heat entirely and quickly pour in the egg mixture, tossing constantly to create a creamy sauce without scrambling the eggs.
Thin the sauce with a splash of the reserved pasta water if needed and serve immediately with a final pinch of sea salt.