In a bowl of boiling salted water, cook your spaghetti to al dente.
While the pasta is cooking, place the diced guanciale in a dry pan over medium heat to render the fat and cook until crispy golden brown.
In a separate bowl, crack in the 3 egg yolks along with the pecorino and a hefty amount of freshly grated black pepper. Mix well into a paste.
Once the pasta is cooked, transfer pasta, crispy guanciale and a splash of the pasta water into the bowl with the eggy mixture and tosst well to combine. Add more pasta water to adjust the consistency of the sauce, if needed.
Top with more cheese and pepper to serve.