Hi Minnie24,
The Dessert Party is a great way for your guests to view Illuminations, and eat really great desserts
We originally had our dessert party scheduled for the Japan Terrace since we had such a small amount of people (8), but a couple weeks before my wedding my dessert party coordinator called and moved us to the UK Lower Terrace as there was something else going on over in Japan. They have a variety of places to choose from to have your Dessert Party but you have to pay a per person minimum for certain locations. Example, Uk Upper Terrace is a 50 person minimum, which means you have to have at least 50 people to book that venue. (Not really sure if it's a 50 person minimum, just making an example)
They also offer a variety of dessert menus, we chose Old World Classics in Minitures....which consisted of mini eclairs, fruit tarts, brownies, tirimisu, and cannolis. They have a variety of different choices for different prices, I think ours was close to $20.00 per person.
To get started I would get in contact with Epcot Catering and start working with them.
Let me know if you have any other questions.