My nephew wanted a dinosaur-inspired cake, and I couldn't find any cake pans or ideas for a dinosaur that didn't look cartoon-like. Online, I found some ideas for this Volcano Cake, and embellished with some decorating and landscape.
The base cake is a simply 13"x9" oblong cake. The "volcano" is from a Wilton Wonderpan (which is advertised as a pan for simulating a barbie doll hoop dress - whatever). The landscape was done with plastic dinosaurs and shrubs I got from the party store bins, and from my nephew's toy chest (washed, of course).
The frosting was simply two cans of store-bought vanilla whipped frosting, colored with Wilton food coloring paste (paste will give you brighter colors without watering down or altering the flavor of the frosting).
It's helpful to make sure the two cake parts are completely cooled before stacking them - and to put a smear of thick frosting between the two cake surfaces, to make sure the "volcano" doesn't move or fall off when the cake is carried.
For the "volcano" eruption: - Find an empty Rx pill bottle or shot glass that about an inch or so wide, by 2 or 3 inches tall (cylinder) - Cut a reservoir into the top of the "volcano" cake big enough to embed the cylinder (so it can just barely be seen) - Put 2-3 teaspoons of baking soda (not baking powder) into the cylinder - Separately, prepare a small package of red Jell-o (Strawberry or Raspberry is fine), add about 4 oz of lemon juice to it, and let the mixture set slightly (e.g. still pourable, just a little thick). If it gets solidified before you need it, just put it in the microwave for 30 seconds at a time until it's liquified. - When you want the cake to "erupt" simply pour the mixture into the cylinder and fill it up to the top rim of the "volcano," stand back, and let the kids watch. It's helpful to use a liquid cup measure to pour out of (or other pitcher-like conatiner with a spout, to get it into the tiny cylinder without spilling).
The "lava" will look thick and frothy in the end. There should be enough baking soda left to do a second "eruption," though you may have to use a straw or stirrer to mix up the baking soda the 2nd time (it can get caked into the bottom of the cylinder, no pun intended).
The "lava" will also not really taste that good (kind of like very sour jell-o with an overpowering baking soda flavor). But it's edible, and doesn't really soak into the cake.
My 5 year old nephew (and his little friends) seemed to love it and be impressed. I guess I'm lucky they're only five.