par-tay!

Lindsey - thanks for the fun idea. I'm still not a great cake baker and some aspects of this left some room for improvement, but it was a fun cake for our party. You can get the full "from scratch" recipe here and some other ideas here and here and here.
I took some shortcuts and just started with 3 white cake mixes and 12 disposable cake pans. Fill each pan with 2/3 cup cake batter mixed with neon food coloring (I got some cool colors at ABC Cake Decorating). I had six colors and made two layers of each.
Bake at 350 degrees for 10-12 minutes, three layers in the oven at a time.

Then place a 8"round cardboard (you'll need it to transfer the cake to a plate later) onto a cooling rack over a cookie sheet and drizzled the fudge sauce over each layer . . . .
. . . until it looks like a big stack of pancakes and syrup. I stopped at 9 layers.
If I had more time, I would have made a good frosting recipe, but I was running short of time and grabbed a can of ready made frosting. Didn't I already say I've never been able to frost a cake properly? Here's the proof of that. (In my defense, though, this didn't have straight edge sides.)
Nevertheless, the end product was fun. Here's the fudge sauce recipe:

3 cups sugar

1/2 c cocoa

2 sticks unsalted butter at room temperature

12 oz. can evaporated milk

1 T. vanilla

Mix everything except the vanilla in a saucepan and bring to a full boil. Reduce heat to medium low and cook until icing has thickened slightly, about 3 minutes (it will resemble chocolate syrup but will thicken as it cools) . Stir in vanilla. Let the icing cool until thick enough to spread, but still pourable (I let it cool almost an hour).