Unfortunately, our Reservation Finder does not support this. We do not offer a tool that can help you locate reservations for dessert parties and other special events.
Although adding support for special meals and events is on our list of potential future enhancements, Disney handles these events differently, and adding support to find (and let you reliable book) those reservations would not be simple.
Your best bet is to check back for availability manually via Disney's website. As with most Disney World meal reservations, the likelihood of finding a spot normally increases the closer you get to your desired date (including the day before and the day-of).