So, what’s so special about hot cakes? It may be that whoever coined this phrase was referring to an actual, and popular, type of cake.
Alternatively, were hot cakes may chosen arbitrarily as the acme of customers’ desires, much like sliced bread was chosen as ‘the best thing since sliced bread’.
There’s a reasonable case to be made that the phrase derived as a reference to real cakes.
In 1830s America church bake sales and fairs often sold pancakes, known as Hot Cakes or Johnny Cakes. These were much nicer hot than cold and usually sold as soon as they were made.
The phrase ‘selling like hot cakes’ came to be used to describe any item that was selling very well.
The first example I can find of the phrase in print is in the New York newspaper The Buffalo Bulletin, October, 1830:
Pepper boxes quite a heap,
And 2000 Rattle Boxes, diced cheap,
Going like hot Cakes: at one cent a-piece.
Other newspaper entries from soon after that refer to ‘selling like Johnny (or Joney) cakes’.
The first known reference to selling is found in C. F. Briggs’ novel, Adventures of Harry Franco, published in New York in 1839:
‘You had better buy ’em, Colonel,’ said Mr. Lummucks, ‘they will sell like hot cakes.’
The expression came into use during Covid lockdowns when panic buying of household items was rife.
Having become an established part of the language in all English-speaking parts of the world by 1900, it is still in widespread use.
See other phrases that were coined in the USA.