Use high-quality guanciale for the best flavor. If unavailable, pancetta can be substituted, but the flavor will be slightly different. Freshly grated Pecorino Romano is essential for the authentic flavor of this dish. Pre-grated cheese will not melt properly and will result in a grainy sauce. The pasta water is crucial for creating the creamy sauce. Add it gradually, as needed, to achieve the desired consistency. Don't be shy with the black pepper! It adds a necessary kick to balance the richness of the guanciale and Pecorino Romano. Serve immediately to prevent the sauce from drying out.