They are green apples with a candy coating, and on top of that has a dripping layer of white chocolate (colored green for dramatic effect, of course!)
Also available are caramel apples with the white chocolate drip.
These are usually only available on Halloween, but last year they were also being sold on Friday the 13th as part of a special Villains only celebration at Disney's Hollywood Studios. 2013 was the year of "limited time magic". That is, it was a year where each and every week there was a different surprise event going on and Friday the 13th being invaded by Villains happened to be one of these celebrations.
Does that mean that since this year, every week is "normal" (way to be lame, Disney) we will not be seeing these tasty apples until October? How would I ever be able to live with myself?!
The Candy Cauldrin is a shop at Downtown Disney often showcases their talented apple artists by having their work prominently featured in the bakery window. I wouldn't be surprised to see once of these in the window sometime...