Are you trying to buy a whole cheesecake?
The Publix grocery store chain sells cheesecakes in its bakery..
If you want something nicer, I like the Cheesecake Factory, where you can buy a whole one or just go there for dinner/lunch and have a slice. That will be more for sure, but the portions are giant.
If I were on vacation at Disney, I would just pick a restaurant on property somewhere that offers cheesecake and save the time of driving somewhere.