Instead of a full bottle of wine, as is used in the classic version of this recipe, we use half a bottle of wine; the remaining wine can be enjoyed with the pasta. We added beef broth, which is milder and less acidic but nonetheless flavourful, to the reduction liquid. Adding butter to coat the pasta when the liquid has almost fully evaporated serves to cut the acidity and impart a creaminess to the spaghetti, while the Parmesan shavings bring a delicious umami flavour to this Italian dish.