We threw a birthday party for my older daughter this past weekend – she just turned 5. Since she’s on a science kick, we decided to make a theme of it. We hired Mad Science to come and entertain the kids, we came up with a melee of easy scientific activities to do with the crowd, and I decided to make an erupting volcano cake. I’d read about the idea on the internet, and thought it sounded very cool.
I researched a lot, watched some videos on YouTube and even corresponded with two of the people who’d made the videos. I made a test cake on my daughter’s actual birthday to double check the lava concoction, and the party cake came off without a hitch.
It was a big hit, and several people have asked me to share my recipe and method. Here’s a photo of the finished product, and I will post the recipe below. If you attempt it, I’d love to see pictures.
Thanks go out to my daughter for inspiring the project, my always-patient husband and co-conspirator, my sisters, who both share my fascination with dry ice, my mother-in-law for the new Kitchen Aid — just in the nick of time, my mother for the baking gene and the moral support, and last, but not least, the YouTube ladies who came to my aid.
Easy Easy Chocolate Cake
(each recipe makes 1 16″ round OR 2 9″ rounds OR a bundt cake and a 6″ round) Adapted from “The Perfect Cake”
3 cups flour (425 grams)
1/2 cup Hershey’s cocoa
1 tsp salt
2 cups granulated sugar (400 grams)
2 tsp baking soda
2 tbsp white vinegar
2 tsp vanilla
1/3 cup unsweetened apple sauce
1/3 cup canola oil
2 cups lukewarm water
Preheat oven to 350. Spray your pan(s) generously with cooking spray. Put the dry ingredients in a bowl and whisk to combine. Carve out four little indentations (“wells”) in the dry mix. In each well, place a different wet ingredient, then cover the whole thing with the water and mix well to combine. Yes, it’s really that easy. Pour the batter into your prepared pan(s) and bake. Baking time will vary depending on the pan type, but it’s about 30 minutes for a 9″ round. Cake is done when a toothpick comes out clean. Let cool in the pan for about 15 minutes and then unmold onto a cooling rack.
When made properly, this cake is very sturdy and easy to manipulate and decorate. If you have a scale, do weigh the flour and sugar. It does make a difference.
Cookies & Cream Filling
(this is a great cake filling – its so easy to make and kids always love it. This recipe makes a lot – like 6 cups – so if you’re making a small cake, halve the recipe) From “The Whimsical Bakehouse”
2 1/2 cups heavy cream
1/4 cup confectioner’s sugar
1/2 tsp vanilla extract
20 chocolate sandwich cookies (I like Newman’s Own), crushed into medium size pieces
Beat the cream, sugar and vanilla in the bowl of an electric mixer at high speed until stiff. Gently fold in the cookies. You’re done.
Makes 2 1/3 cups, plenty if you’re just using it to level your layers, make lava and do some decorating.
1 stick of butter or Earth Balance
1 box of confectioner’s sugar
1/4 cup of milk (skim, whole, soy, whatever)
1 tablespoon vanilla
1/4 tsp salt
Using the paddle attachment on your stand mixer, cream the butter at high speed until light and fluffy. Mix in the sugar alternating with the milk, beating well after each addition. Beat in the vanilla and salt, then add a bit more milk if needed to reach a good consistency for spreading.
Reserve half of this frosting to mix with crushed Oreo cookies if you want the “dirt” effect on your volcano. Makes about 3 cups. If you’re making a big cake, double it.
4 cups confectioners sugar
1 1/3 cups Hershey’s cocoa
1/4 tsp salt
1/2 cup milk, plus additional (skim, whole, soy, whatever)
1 tsp vanilla
4 tbsp butter or Earth Balance
Whisk together the sugar, cocoa and salt. Add the milk and vanilla and beat with the paddle attachment of your stand mixer until blended and smooth. Beat in the butter and then add milk to reach your desired consistency.
1. Bake the cakes and let them cool completely. For my cake, I made two 16″ layers, three 9″ layers, a 6″ cake (split into 2 layers), and a bundt cake (split into 2 layers). I had to quintuple the cake recipe to get all the cake I needed. Split cake layers as desired.
2. Make the buttercream and set aside some white buttercream for lava and decorating. Put the remaining buttercream into a pastry bag fitted with a coupler. It’s a good idea (I didn’t do this, but it would have been easier) to mix some cocoa into the buttercream so it will match the color of the chocolate frosting.
3. Make the Cookies & Cream filling.
4. Fill the cake layers – first pipe a ring of buttercream around the perimeter of each layer, then fill the inside of the ring with whipped cream.
5. Use a sharp, serrated knife and a spoon and carefully excavate a hole in the middle of the volcano and insert a long, thin vase or glass (ideally at least 8oz) that will hold the lava mixture.
6. Frost the cake with chocolate frosting. I suggest a layer of plain frosting, and then thin out the remaining frosting and mix in some finely crushed chocolate sandwich cookies. Pour that over the cake for a cool, gravelly effect.
7. Use good quality gel food colors to tint some of the remaining white buttercream red, orange and yellow in three separate glass bowls. Microwave each bowl for just 15 seconds to get it to a thick liquid consistency and pour it over the top of the cake.
8. Decorate the cake. The buttercream recipe here will work OK for piping, though it’s not as stiff as an icing with a higher fat percentage. My husband sculpted Tasha (from the Backyardigans) out of Wilton’s Fondant.
9. To make the lava, mix together about 2 tbsp marshmallow fluff with 2 tsp warm water. Stir until smooth. Tint red with food coloring. When it’s time to serve the cake, toss a handful of dry ice chunks into the embedded glass inside the cake, add the fluff mixture, then pour hot water into the glass. The volcano will erupt with smoke and soon, the lava mixture will bubble to the surface and spill over onto the cake.
Do try to keep the cake chilled if you aren’t serving it right away, since there’s whipped cream in there. Good luck! To see more pictures, click here.