There is a slight difference between the two Italian pork products. Guanciale vs Pancetta - pancetta is pork belly & guanciale is from the jowl of the pork cheek. Both are fatty, with guanciale being traditionally more fatty & is the star of a good carbonara recipe. For this recipe, both will work just fine so use your favorite or what you have on hand. Prosciutto however I do not recommend as an alternate for pancetta. Prosciutto is traditionally not cooked until crispy and is sliced thinly. It will not render the fat needed for this dish nor the small dice that make the crunchy bits irresistible.