Cacio e Pepe
The quality of the pasta matters! Rummo's spaghetti is perfect and can be found in regular grocery stores. Rummo pasta is dried at a low temperature for a longer period of time to preserve nutrients and the pasta is trafilata al bronzo (pasta comes through bronze nozzles) which leaves the surface of the pasta rough and allows the sauce to absorb better. If you have the time, it's worth making the pasta yourself. The starch in the flour makes the sauce even thicker. Basic recipe for pasta dough here.