Once upon a time, butterscotch was the darling of the American sweet tooth, casting its golden glow over puddings, pies, sauces, candies, cake frostings--you name it. Now there are people who've never had so much as a single, sorry instant butterscotch pudding.
This must be an oversight, America. Sure, maybe your doctor doesn't want you to eat too much of it (your dentist either), but fresh butterscotch is overwhelmingly rich, mellow and seductive. Flavorwise, it's the boss.
In my ill-informed youth, the only butterscotch I knew was either a sauce or a pudding. When I first encountered butterscotch balls, I remember thinking, "Hey, cool, they've figured a way to make a butterscotch-flavored candy."
Actually, I had it backward. Butterscotch candy had come first--the butterscotch flavor develops naturally when you boil sugar syrup and butter together to a high enough temperature to make hard candy. It's a combination of two flavors: browned sugar, otherwise known as caramel, and browned butter. The latter results from what chemists call the Maillard reaction, in which sugars and proteins react under heat to create roasted and browned flavors.
This is why butterscotch has so often been combined with other roasted ingredients. Nuts, such as pecans, are typically roasted; rum and Bourbon contain caramel; maple syrup has undergone the Maillard reaction.
If anything is certain about butterscotch, it's that this flavor was not created by design. It was a byproduct of a technique that made candy-making just about foolproof, even for people who weren't skilled confectioners. The problem in candy-making is that once syrup has been heated higher than about 250 degrees, its natural inclination is to "seize up" as it cools, turning into rock-hard crystals rather than brittle, glassy candy. In the 17th century, French candy-makers had discovered that fat has the handy property of getting in the way of crystallization.
Acid ingredients accomplish much the same thing--in the 18th century, adding an acid such as cream of tartar to sugar syrup was called "greasing" it--by breaking some of the sucrose molecules into glucose and fructose sugar, thereby cluttering up the solution for would-be crystals. This is one reason for all the many sweet-sour hard candies, such as lemon drops and Life Savers. Probably it also explains why a lot of old-time butterscotch recipes call for a little vinegar or lemon juice, and maybe even how a bit of lemon peel flavor came to be traditional in English butterscotch candies.
Molasses retards crystallization too, by altering the ratio of glucose to fructose. Conveniently for butterscotch makers, molasses contains caramel and even some roasted Maillard-reaction flavors of its own, because it's the byproduct of the repeated boiling by which sugar is refined; in effect, it's a very dark caramel with a distinct burnt edge and a bit of sharpness. Because molasses is so strongly flavored, butterscotch recipes rarely use it straight, only in the diluted form of brown sugar, which is basically refined sugar crystals thinly coated with molasses.
So a really cautious, or insecure, candy-maker might throw all these things into the mix: butter, an acid ingredient and molasses. As it happens, until highly refined sugar became inexpensive in the middle of the 19th century, most sugar--certainly the sort of sugar ordinary people had access to--was more or less brown, so the molasses issue pretty much took care of itself.
Though the name "butterscotch" didn't appear until 1885, the product was probably being made in the early 18th century, maybe even before that. In "Sugar-Plums and Sherbet: The Prehistory of Sweets" (Prospect Books, 1998), Laura Mason draws attention to a brand of hard butterscotch called Everton toffee, which goes back to 1753. (The word "butterscotch" has nothing to do with Scotland, by the way. "To scotch" means to cut or score something; when butterscotch candy was poured out to cool, it was "scotched" to make it easier to break into pieces later.)
In the late 19th century, Americans started making butterscotch-flavored sauce, one of the mainstays of the old-time soda fountain, and then followed up with a profusion of butterscotch pastries and other sweets. Most of them have faded, but an underground of passionate butterscotch lovers survives.
For proof, there's Diana Dalsass' "The Butterscotch Lover's Cookbook" (Buttercup Press, $17.95), which gives a lot of luscious-sounding recipes, such as butterscotch streusel apple sour cream pie. Nearly all are based on crushing up butterscotch candies, though, rather than making butterscotch from scratch. The book includes a passionately researched list of sources for buying them.
Why don't many people make butterscotch sauce or pudding today? Particularly if you don't trouble to cook the butter to the point of browning (around 240 degrees), as some recipes don't, it's a splashy effect with relatively little risk of failure. Butterscotch is forgiving.