What is butterscotch, other than the favored hard candy flavor of grandmothers? F. K. Robinson's Glossary of Yorkshire Words from 1855 describes it as "a treacle ball with an amalgamation of butter in it". Mmm. Who doesn't love some them treacle balls with amalgamations of butter?
In more scientific terms, butterscotch is butter and brown sugar boiled together, sometimes with the additions of corn syrup, vanilla, cream, salt, or treacle (an uncrystallized sugar syrup). It's essentially soft toffee that's only been cooked to the "soft crack", not "hard crack", phase.
I love butterscotch but for some reason, growing up, my household never used it in baking. I think we just didn't know what to do with it. We thought it was better left as soft serve dip. So it was a long time before I tried oatmeal scotchies, those thin, chewy oatmeal cookies that are liberally laced with butterscotch chips.
In my mind, oatmeal and butterscotch are not an obvious combination. It turns out that they play extremely well together, and regular old scotchies are a great cookie. The butterscotch chips definitely put them on the sugary side, though the oats restrain them from being tooth-achingly sweet. But there is something about regular scotchies that makes me want to eat them in cold weather (perhaps because they look like one of my wonderful warm ugly knit sweaters?), so I decided they needed a little revamp for summer.
To this end, I added coconut palm sugar and some spiced dark rum. The resulting cookie has the same thin, pliant shape and texture as the original, but with a hint of the tropics. Because they are a lattice cookie, make sure you let them cool for at least 10 minutes before transferring them from the baking sheet. If any do happen to shatter, save the pieces: they make an awesome topping for vanilla ice cream.