Is there such a thing as “unsweetened condensed milk”?

That from reader Chana. In fact there is, it’s simply called “evaporated milk” and it can usually be found in the same section of the grocery store. Evaporated milk was a later development than (sweetened) condensed milk for the simple reason that the manufacturing is more difficult. Without the bacteria-killing sugar in the mix, there are more processing (specifically sterilizing) steps involved.