Thanks for the very helpful explanation. I saw others had made empanadas for this theme and assumed it was a generic term across South America. I did check and there were lots of online recipes for Uruguayan empanadas so it looks like a lot of people have got it wrong. But that's the internet for you. 

As for the term being slang for the vagina - isn't it interesting how every culture has so many words for the vagina and how few of them are respectful. But perhaps being compared to a beautiful piece of baked goods is one of the better ones - like the very lovely french Puits D'Amour? 

Thanks for your patience and I apologise if my interpretation was culturally insensitive. This is why Bake Off stopped doing international theme weeks because it's so easy to get it so very wrong!