I would think if they have it in the kitchen they will make it for you. DW has certain allergies to food and is always asking to have " special" things made for her , based on what she see on the menu. It has never been a problem.
One year the executive chef at Chef Mickey's came out to help with a question. He told her that even on a buffet they would prepare special items. He had a great knowedge of all kinds of special food needs.
Bottom line don't be bashfull ( no pun intended) . If the server says no ask the manager. I have never had a special food request turned down at WDW . BTW last year my wife wanted an item on the kids menu( at San Angel Inn) and they served it to her at the kids prices !!