Since the recipe originated across the pond, I had to do a bit of searching to find some of the key ingredients. For your edification: Golden Syrup, Caster Sugar and Dark Muscovado Sugar.
So golden syrup reminds me a bit of Karo syrup with the color of honey. Found it at my local Kroger in the international foods aisle; it's sweet and sticky, like you might expect. The Dark Muscovado sugar looks and smells like gingerbread. It's like a spiced dark brown sugar; seems like it would be awesome in holiday recipes. The Caster Sugar is basically just really super-fine white sugar; would be great in iced tea. I was able to track down both sugars at Central Market. Note: They weren't cheap. These one-pound bags cost 7 bucks each! It was worth it for the experiment, but probably not on a regular basis.
The original recipe gave the measurements in grams, so I was really glad I own a food scale. Sometimes I wish we could just all be on the metric system...accuracy is key in baking!
So the cupcake recipe was supposedly for Devil's Food, but these seem more like a sort of cocoa spice cake to me. It's definitely not as sweet as most of the cakes I'm used to making (but the frosting makes up for that). Also the recipe said it would make 12-15 cupcakes, but I got an easy 20. They baked up perfectly at 20 minutes.
The dual-flavor frosting (fondant and cream cheese swirled) is meant to mimic the filling inside a Cadbury egg. Mine didn't turn out quite as pretty as the originals, but overall I was happy with the project. And I learned something new, which is always fun!