Yesterday, I made an ADR for dinner at CRT for 1/24. I asked the CM I spoke with in dining if I could still order the Cinderella slipper dessert. I am attending a convention, and the friend I'm going with has never been to WDW. I wanted to get this for her as a special treat. Anyway, the CM couldn't find any info, but he gave me this number to call: 407-824-7091. When I called, they answered Magic Kingdom dining operations, or something like that. When I asked about ordering the slipper, she confirmed my ADR in their system. Then she asked if it was a special occassion, such as birthday or anniversary. She said she didn't need a credit card (I did have to give a cc# when ordering these at GF before). The cost will just be added to our dinner.
So, looks like they are still available on a pre-order basis.
Hope this helps!
Christy