Bring a large pot of water to a boil. Add pasta and cook according to package directions.
Meanwhile, place pancetta in a large, cold nonstick skillet. Cook over medium heat, stirring often, until most of the fat is rendered and the pancetta is crisp, about 5 minutes. Add chicken; cook, stirring constantly, until warmed through, about 1 minute. Remove from heat.
Whisk egg yolks, ¼ cup cheese, pepper and salt together in a large heatproof metal bowl. Using tongs, transfer the cooked pasta directly from the boiling cooking water to the bowl with the egg yolk mixture; toss gently until the cheese melts, about 30 seconds.
Place the bowl with the pasta over the pot with the boiling cooking water; cook, stirring constantly, until the sauce thickens and coats the pasta, about 1 minute. Remove the bowl from the pot; stir in the pancetta mixture.
Divide the pasta among 4 bowls; top with the remaining ¼ cup cheese. Garnish with additional pepper, if desired.
