Bring a large pot of salted water to a boil and cook the spaghetti until al dente according to package directions.
While the pasta cooks, add the diced pancetta to a large skillet over medium heat and sauté until crisp and golden.
Remove the pancetta with a slotted spoon, leaving the rendered fat in the pan, and add the cubed chicken breast.
Cook the chicken for 5-7 minutes until browned and cooked through, then add the minced garlic for the final 60 seconds.
In a small bowl, whisk together the Greek yogurt, egg yolk, sea salt, and black pepper until smooth.
Reserve 2 tablespoons of pasta water, then drain the spaghetti and add it directly to the skillet with the chicken.
Remove the skillet from the heat and quickly stir in the yogurt mixture and reserved pasta water, tossing constantly to create a creamy sauce.
Fold in the crispy pancetta and garnish with fresh parsley before serving immediately.