My husband is a Chef and it totally tugs on my heart strings to hear about a child aspiring to be a Chef!
So, I've done some research and the program was called Grand Adventures in Cooking at the Grand Floridian. I kept seeing conflicting information on the websites so I called the Grand Floridian and Disney Dining, the latter being who you would purchase the tickets from to attend the event.
Disney Dining told me that the program is no longer offered on a continuous basis, but that during Epcot's Food & Wine Festival in the fall it will be available again.
If you ever have a chance to visit Epcot during the Food & Wine Festival go for it! For Foodies everywhere that festival is tops! My family visited this past fall and had an amazing time seeing and trying the food from all over the world and you can attend cooking demonstrations there as well.
I'd like to mention also that my kids took cooking classes during a Kitchen convention in Atlanta this past year...maybe keep an eye out for those conventions and see if they offer something similar!
Good luck to your little Chef!