Erupting volcano cake with fizzing lava

Erupting Volcano Cake featuring The Good Dinosaur

February 14, 2020

Erupting volcano cake anyone? We’re always looking for ways to bring a little magic to our everyday lives. So, when our son requested an erupting volcano cake for his fourth Birthday, I happily accepted the challenge! Now, how exactly does one make a cake erupt…?

Two cakes?

It quickly transpired that making a cake erupt is no mean feat. I had visions of elaborate contraptions contained within the cake, considering whether hiding a chocolate fountain in the centre might be viable. Eventually I came to the reluctant conclusion that it would in fact be ‘simpler’ to create two cakes. The first would look like a volcano, and feature an orange ‘lava’ centre. The second, would actually erupt.

The reason for doubling my workload, was the simple fact that it transpires that bicarbonate of soda is brilliant for ‘eruptions’. However, it tastes foul – this hadn’t occurred to me, so hopefully saves you the dubious taste test that I indured! As such, the erupting volcano cake would in all likelihood be inedible. Cue the need for a backup cake.

Since our son is as big a Disney fan as we are, I wanted to bring a little something extra to the cake. The Good Dinosaur seemed like a natural choice for a volcano cake, and I opted to use plastic cake toppers. We ordered ours from eBay in a set that included all the famous faces; Arlo, Spot, Butch and many more.

The main Volcano

To make the main cake I baked five chocolate sponges and one smaller, orange coloured, vanilla sponge. To assemble, I cut circles of decreasing sizes out of the sponges and stacked them. I then cut a circular hole out of each layer, and replaced it with a disk of orange sponge. For the very top layer, I left the hole empty to creat the mouth of the volcano.

Between the layers I spread marmalade and chocolate orange buttercream. Finally, I haphazardly iced buttercream around the cake, and applied strips of chocolate fondant. I tucked each strip into the top of the cake, leaving the orange ‘lava’ on display. Word of warning; this used a ton of fondant! Or, more precisely around 1kg.

Buttercream grass, malteser rocks and crunchie lava rocks adorned the base. Meanwhile, Arlo, Spot and friends added the finishing touch.

The erupting volcano cake

The erupting volcano cake was a much speedier, and more haphazard, process. Dry ice isn’t readily available near us, so our explosion relied on a little bit of science. Because of this, the second cake needed to be built around a cup to enable the experimental eruption to take place. Accordingly, I placed an orange plastic tumbler on an iced cake board and packed cut offs of chocolate cake around it. As a result, the cake could have been eaten if our son desired (although he followed our recommendation that it didn’t taste the best!). I again covered the cake in chocolate fondant, cutting a hole for the cup, and decorated. For this cake, Thunderclap had pride of place in the danger zone!

To make the volcano erupt, I filled the cup halfway with warm liquid orange jelly. Next, I filled the cup to the brim with lemon juice. Finally, for the ‘eruption’, I added a tablespoon of bicarbonate of soda and mixed. Place the cake board on a tray to catch the lava!

Seeing the joy on our little dude’s face as the volcano fizzed and bubbled was so magical! Now to prepare for next year’s cake off…

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