Yes you can, but you will have to call the special events area. I looked into this when we had a big group going, however, it is expensive. You pay to rent the venue, then there is a per person charge for the food and there is a minimum number of people (you don't have to have that many people but you do have to PAY for that many people). At the time I looked into it the cheapest area was $250 for the rental (I think that was lower UK) and about 19/ person for dessert, which was the least expensive dessert package. If I recall correctly the minimum was 20 people so you were looking at roughly $650.
I found out at you can do basically anything if you have enough money. She was suggesting a dessert party at AK at an area where you can watch the Jungle Jam Parade, followed by a private safari ride - $$$$$$.