Here's what you'll need to make a volcano cake (inspiration taken from this post by The Bake-Off Flunkie):
1. A cake (obviously). I went with two 9" round cakes on top of each other but a 9"x13" cake would give you more room to play.
2. Rice Krispies (I just followed the instructions on the box regarding how to make the treats with marshmallows, butter, etc.)
3. Frosting (I used both buttercream and chocolate buttercream - recipe below)
4. Brown sugar (for sand)
5. Food coloring (green for grass, blue for water, brown and orange for under the sand)
6. Candy (I used chocolate rocks, gummy sharks, and sour starfish)
7. Tongs/gloves and dry ice (make sure you bring an ice chest with you if the store won't supply it for you!)
Step #1 - Make the volcano
I recommend making the Rice Krispies first so you can build your volcano. Once they've cooled and hardened (usually after an hour), use a water bottle, a soup can, or something similar (I used an old Republic of Tea tea bag canister) as the center of the volcano. Start to mold the Rice Krispies around the can to form your volcano. I recommend going with something smaller than what's pictured here because:
Mistake #1 - The taller the bottle/can/etc., the more likely the Rice Krispies and gravity will have it melt off. And don't try to wrap your canister in plastic wrap - that'll only make things worse!
Once your volcano has been formed, stick it in the fridge to harden. I left it in the fridge overnight, just to be safe!
Step #2 - Make the cake
As I said, I made two 9" round cakes but you're free to make the cake however you want!
Step #3 - Make the buttercreams
To make the chocolate buttercream from scratch, you'll need:
* A bar of Ghirardelli unsweetened chocolate (4 oz.)
* 1/2 cup of softened butter
* 1/3 cup of vegetable shortening
* 1 teaspoon of vanilla
* 4 cups of powdered sugar
* A couple tablespoons of milk, depending on the consistency you prefer
(To make the buttercream for the grass, water, etc., it's the same ingredients and process, minus the chocolate.)
To make the chocolate buttercream, melt the chocolate in the microwave for 30 seconds and then 10 seconds spurts after that, as you don't want to burn the chocolate. Let the chocolate cool completely before adding to the creamed butter and shortening. Add the vanilla, then slowly add the powdered sugar until combined. I only used 1 Tablespoon of milk before I got the consistency I preferred but you can use up to 4-5 Tablespoons.
Step #4 - Frost the cake
The chocolate buttercream will cover the volcano but will also go in between your layers of cake and also around the sides (you can see that if you don't melt the chocolate completely, you'll have little pieces of chocolate showing but eh, it kinda looked like dirt!)
I sculpted one side of the cake to slope down so the water would have a place to crash on the beach. Just cut off a piece off the top cake on a diagonal.
As for the non-chocolate buttercream, divide it into three bowls - a little bit for the green grass, and then half-and-half blue water and tan sand. In order to get this sand color, I mixed brown and orange Wilton gel food coloring. Frost the top of the cake and the slope you carved out.
To give it a 3-D effect, cover the top with brown sugar or Sugar In The Raw to have it look like sand.
To make the water, I used sky blue Wilton gel food coloring and Wilton piping tip #108. Using a toothpick, I flicked the blue frosting in different directions so it would look more like waves.
Mistake #2: The blue frosting was too warm so it started sliding off the sides of the cake! Make sure the frosting is a bit on the cold side so it doesn't melt off.
Stick the cake in the fridge so the frosting can harden. However, if you wait too long...
Mistake #3: ...you'll end up staining your cake board because of all the butter and shortening in your frosting. So don't put the cake on your cake board until you're absolutely ready to assemble the rest of the cake!
Step #4 - Assemble the cake
Once you're ready to present the cake, carefully place your volcano on top and using Wilton tip #233, pipe the green grass around the volcano, on the volcano, wherever you like! I found it was very helpful in covering up mistakes!
Gummy sharks, chocolate rocks, you could even add palm trees to help this desert island cake feel a little more realistic!
Now in order to make the smoke come out of the volcano, fill up half of the canister with hot water. Very carefully drop in your dry ice (either with gloves or tongs) and note that if you have birthday candles below where the smoke is pouring out from, the candles will be extinguished!
And that, my friends, is how you make a volcano cake. Anybody want a slice??
TOTAL COSTS: About $36
$10 for 10lbs. of dry ice from Tym's
$8 for gummy sharks, starfish, and chocolate rocks from Sweet! Hollywood
$3 for two boxes of cake mix (that's right, I didn't make the cake from scratch!)
$1.99 for Rice Krispies
$1.50 for marshmallows (for the Rice Krispies)
$3.99 for Ghirardelli unsweetened chocolate
$.99 for butter
$4.39 vegetable shortening
$2.49 powdered sugar (I used an entire 2lb. bag!)
Vanilla and brown sugar made from scratch, milk and food coloring already on hand
TOTAL AMOUNT OF TIME: 2 1/2 hours + overnight
15 minutes to mold the volcano + overnight to harden
1 hour to make the vanilla and chocolate buttercreams
1 hour to decorate the volcano, dirt, sand, and water
15 minutes to assemble the volcano, candy, and grass
EASY-PEASY SCALE (1 super easy - 5 very difficult): 4 out of 5
Warm weather will not be your friend when making this cake, as the frosting will want to melt off the cake. As long as you keep the cake cold until it's ready to be eaten, you'll be fine. It's easiest to break it into sections so it doesn't seem as daunting: make the volcano, make the cake, make the frosting, assemble. And be careful with the dry ice - do NOT touch it with your bare hands or you'll burn your skin!