Slice your guanciale into 1/4" thick slabs then 1/4" strips and place in a cold pan. Turn the heat up to high and cook for 3-4 minutes until the fat has rendered out and guanciale is crispy.
Add a splash of white wine to stop the cooking process (optional), then add your crushed tomatoes. Season with crushed red pepper, salt, and pepper to taste, and simmer on low while your pasta cooks.
Cook pasta to al dente in salted boiling water, then add immediately to the sauce and mix to combine.
Add a handful of grated pecorino and continue mixing to thicken up the sauce, adding pasta water if too thick. Top with more freshly grated pecorino and enjoy!