The only thing I've found online is Caramel Appletini Cupcakes and, although they look and sound amazing, the caramel seems to be the star. http://iheartcuppycakes.com/2008/05/08/caramel-appletini-cupcakes/
There are Granny Smith apples in the cupcakes, but caramel filling, caramel apple (vodka) frosting and caramel drizzle. I've never had an Appletini, but I'm hoping to find something that shouts the sour apple part.
Appletinis are sneaky! They're so good you want a few, then all of a sudden - BOOM! - they hit you like a rocket!
You might want to throw some sour apple schnapps (DeKuyper Sour Apple Pucker) in there instead. You will get more flavor than with the vodka. Or hey, use both!
i was going to suggest sour apple pucker as well.