Bring a large pot of filtered water to a rolling boil and season generously with sea salt.
Add the chickpea spaghetti and cook until al dente, usually 7-9 minutes; reserve 0.25 cup of the starchy pasta water before draining.
While the pasta cooks, whisk the egg yolk and grated parmesan in a small bowl until a thick, pale paste forms.
In a large skillet over medium heat, sauté the diced pancetta until the fat renders and the edges become crispy and golden.
Add the diced chicken breast to the skillet with the pancetta, seasoning with sea salt and black pepper, and cook until browned and the internal temperature reaches 165 degrees.
Stir in the minced garlic and cook for 30 seconds until fragrant, then remove the skillet from the heat source.
Immediately add the hot pasta and the reserved pasta water to the skillet, tossing to combine.
Slowly pour in the egg and cheese mixture, whisking or tossing constantly so the residual heat creates a silky, creamy sauce without scrambling the egg.
Garnish with freshly chopped parsley and an extra crack of black pepper before serving immediately.