Cook the spaghetti according to package instructions until al dente. Drain and set aside.

In a large pan, cook diced bacon over medium heat until crispy. Remove bacon and set aside, leaving the rendered fat in the pan.

Cook chicken breasts in the same pan for 4-5 minutes per side, or until browned. Remove from the pan and let rest.

Add chopped onion and minced garlic to the pan. Sauté for 2-3 minutes until softened and fragrant.

In a bowl, whisk together heavy cream, parmesan cheese, pecorino romano cheese, and egg yolks to form the sauce.

Cut cooked chicken into bite-sized pieces and return to the pan. Pour the cream mixture over the chicken and stir to combine.

Add the cooked spaghetti to the pan, tossing to coat the pasta in the sauce. Stir in crispy bacon, and season with salt and pepper to taste.