It has surprisingly little when you consider that citrus curds have been popular for about 125 years and shortbread for many (many) more than that. You’d have thought that somebody, especially somebody living somewhere in Britain, would have put those two things together in pie form. It seems, however, that this particular somebody never did. It took the recipe R&D team at Betty Crocker Inc. to invent the lemon bar, and indeed they published the first known printed recipe in 1963. To say the things took off after that is an understatement. By the 1970’s everybody was making lemon bars, including my very own grandmother, whose recipe (at least in my mind) has yet to be equalled.