Alright, so the basics. Apparently this is a very popular dessert in Britain. It is made with treacle, or "golden syrup." Treacle can also refer to molasses, but true treacle tart is made with golden syrup. The dessert is basically a pudding pie, there is a crust on the bottom, then the custard on top, then the pastry is latticed on top for a yummy tasting pie that is usually served with whipped cream or ice cream. YUM!
So what is treacle? According to wikipedia and wisegeek.com (yay for unreliable sources!), treacle, or golden syrup, is a by-product of sugar making, more specifically the process of turning sugar cane into juice, or by mixing a sugar solution with acid. I won't go into all the science-y details (even I don't really care about that!), but picture a substance that is very similar to honey in texture and color, but apparently extremely rich (sign me up NOW!). Mmmmmmmm... sugar.
Wisegeek.com describes treacle tart as the following: a rich, shortbread pastry for the base, the filling is golden syrup, breadcrumbs, lemon juice, and some spices (ginger was mentioned), and then the pastry stripes lining the top for more crisp.
I guess treacle is hard to come by in the US, foodnetwork.com doesn't even have a recipe for anything with "treacle" in the title. However, there are a lot of recipes on-line (all Harry Potter themed, for some reason :) that call for light corn syrup or molasses if you can't find golden syrup. Most recipes though said that golden syrup is key, so you can find it on Amazon or in the syrup section at your local Whole Foods (which for me is about 5 hours away in Atlanta. Boo). I think I might try to make it one of these days, using honey, since a few websites said that golden syrup is often used with people who don't eat honey. I also find molasses to have a really strong flavor, so if given the chance, I'll use something else.
Great. Now I'm really hungry. For something really sugary!