Heat a large dutch oven over medium low heat, add the guanciale along with a splash of olive oil, and cook until golden brown. Remove guanciale from the pan and set aside.

Pour the pork fat into a separate container, leaving about a tbsp in the pan. Heat the same pan over medium-high and sear the ground sausage until golden brown. Transfer sausage to the bowl with the guanciale.

In the same pan, add the onion with a tbsp of pork fat and a pinch of salt. Cook until translucent, then add the garlic and cook for another 60 seconds. Add the tomato paste and additional pork fat if needed and cook until caramelized.

Add the crushed tomatoes, Calabrian chilis, sausage, and guanciale to the pan. Mix to combine, bring to a gentle boil, then reduce to a low simmer. Add parmesan rind if using and simmer for 30-45 minutes, stirring every 5 minutes.

Cook the pasta in salted boiling water about 2 minutes shy of package directions. Use a slotted spoon to transfer the pasta to the red sauce, saving the pasta water. Simmer pasta in the sauce for about 2 minutes.

In a large heat-safe bowl, combine egg yolks, cheese, and black pepper. Gradually whisk in 1/4 cup of hot pasta water to temper the eggs.

Taste the pasta for doneness, simming longer if needed and adding more pasta water as necessary. Once cooked, turn off the heat and pour in the egg mixture. Toss to combine, adding more pasta water if needed to achieve a slightly loose consistency.

Serve topped with more pecorino and fresh cracked black pepper.