Do you have any PSs planned? If so, call ahead and modify your reservation to include information regarding SF desserts needed.
Also, when you get to the restaurant, speak to whomever seats you. We did this last year at the Garden Grille Ice Cream Social. The chef came out to speak with us and gave us a choice of SF ice cream or SF cheesecake.
They were both very yummy, but the cheesecake was extraordinarily so.
Just check ahead, or ask when you go somewhere. I think it is available in quite a few places, but not listed on the menu.