Honestly, I would not bother trying to go here for dessert/drinks. The place is a zoo close to fireworks, the desserts are nothing to die for, and the view of the fireworks is not that great (much better view in the park itself). The bar is not up against the glass, the viewing platform outside may be crowded and it's kind of off to the side.
If you are going to make a reservation and actually waste a dining table to just get desserts, you may find that you would not be seated in time for fireworks anyway as people generally make dinner ressies 90-120 min before the fireworks and then stay at their tables even if they are done eating. I have found that if we make reservations to eat close to fireworks time, we are often seated way behind schedule (last time was 50 min past our adr time). We are not interested in the fireworks but it is annoying to have to wait so long for a table.