I found a few more on the new system by just entering Dinner at the Magic Kingdom on July 4th. (I LOVE the new system, but am not sure that this search will help you at all)
Plaza 3:05 (Late Lunch/Early Dinner might work great with your dessert party. Eat dinner now, get a light snack around 7 or so, and be set for the dessert party)
Crystal Palace 9:05 pm (Not sure what time your dessert party is, this probably conflicts with that.)
The search, of course, also turned up the same two that Tigger926 already suggested for you, which probably also will conflict with your dessert party.