My first effort did the same thing. Then I bought a "heating core" and `voila! Perfect. Also, I called Hershey's Kitchens and they said to double the regular recipe for 12x18 pan (much less batter than I expected). And reduce the temperature to 325.
NOTE: the Hershey's bakers said for 13x9 pans, do NOT increase the recipe or change the temperature..

Awesome link! thanks!

I've made this recipe (on the back of the cocoa box) as a 9" round layer cake and it was amazing! My son wants it for his birthday party... for 22 kids + adults. I'm thinking of doing it as two 18x12 layers, baked in separate pans. Any advice? (And I've never "leveled" or "torted" a cake, so I need to keep this simple.)

Bottle King of Ramsey, NJ has Birch Beer kegs. 1/4 - $29.99; 1/2 - $49.99. Order by Wednesday for the weekend.

My husband was at a reunion party at Redd's in Carlstadt, NJ a few years back. It's a restaurant/bar, but has a nice room upstairs. Allows a DJ. I think it might fit your requirements.
Check the space and menus:
http://www.reddsrestaurant.com/events...