Earth Structural Layer Cake

A little while ago, my sister approached me with an idea. She’s doing an education degree, and her and her friends had to give a series of lessons on the geological sciences to a class of primary school kids. One of their lessons involved teaching the kids about the structure of the Earth. One of her friends came up with the idea of presenting a model of the Earth made out of cake. So my sister asked me if I could make a spherical cake with all the layers of the Earth inside it.

I told her I couldn’t do it. “How do you get a sphere inside a sphere inside a sphere?” I recall saying. “Oh yeah,” she replied, realising what it would involve.

I spent the rest of the afternoon thinking about it. I don’t admit defeat. Ever. But especially not with cake. Nothing is impossible is pretty much my baking motto, so to say this cake was impossible left me feeling weird. There had to be a way. A way that didn’t involve carving or crumbing the cake. I kept mulling it over until I had a breakthrough.

There was a better way of doing this that I came up with, but I needed a set of hemisphere tins to pull it off. I didn’t have the equipment, nor the funds to purchase it, so I had to come up with a plan B. Somehow I went from “it’s impossible” to having multiple ideas. Go figure.

Plan B involved baking a cake inside a cake inside a cake. And crossing all fingers and toes and hoping it worked.

Looking pretty promising so far.

There weren’t enough people to warrant a complete sphere, so we went with a hemisphere globe instead. With the inner core, outer core and mantle all cake-d up, it was time for the crust. Chocolate buttercream filled that role.

The rest was left up to marshmallow fondant.

Depictions of the globe, satellite pictures of the Earth, movies… they almost always seem to show the globe featuring America smack bang in the middle. I’m always surprised and excited to see it any other way. So this time I let my home country by the focal point of the cake, and based everything else around it. America still got a little peep around the side.

I added a little white and marbled it into the fondant to make some clouds. I hand cut all the continents from fondant, then painted them with a gel paste mixture using a dry brush technique. This process all up took me about 6 hours and was the most arduous process. Coupled by the fact I was using the world’s tiniest brush. But I think the different colours makes it look much better than if I’d have used plain green fondant.

When I started this cake I was determined for pin-point accuracy. I was going to make every country and every island so damn accurate a pilot could use it as their navigation system. But by the time I got to Europe, it was more like, “Yeah, that’s the general shape.”  By the time I got to the Americas I was wondering if that continent was even necessary. I missed a whole heap of islands above Australia and settled instead for the main ones. Cutting out the countries wasn’t that cake walk I’d imagined it to be.

I finally got to a finished look for the cake and let my sister take it off my hands. She brought me back a slice so I could share a picture of the inside with you all. The red layer is orange Madeira sponge, the yellow is lemon Madeira sponge and the white cake was a vanilla buttercake.

And one of her friends sent me some pictures of their cutting out the cake.

It wasn’t an image of perfection, but I was just relieved that the layers were there. I ran into a lot of trouble with the yellow layer simply through this being one large experiment, so I was expecting it to be a mish mash of terrible proportions.

I’d definitely change a few things next time I tried it. I’d especially love to try the Plan A version of it one day, for that would allow toe possibility of using more moist cake recipes.

I’m told the cake was a massive hit with all the staff and students, so that was definitely a relief!

ETA: Tutorial for making a concentrically layered cake is now here.

169 thoughts on “Earth Structural Layer Cake

  1. That’s gorgeous! Wow!

    I’m always surprised and excited to see it any other way. So this time I let my home country by the focal point of the cake

    I appreciate this very much. /Kiwi

  2. Totally epic!

    Incredible job, I LOVE the attention to detail– it’s functional, it’s beautiful AND it’s edible? Trifecta achieved! You’re amazing.

  3. great geophysics cake!

    What a beautiful cake! I especially appreciate it because I’m a geophysicist, and when I teach about Earth’s interior I use all sorts of cooking analogies. I know it would be extra difficult, but if you could make the mantle part of the cake an actual marble-cake it would be perfect. See for example Allegre & Turcotte’s 1986 Nature paper: “Implications of a two-component marble-cake mantle”

  4. Awesome idea. Would seem a simple idea to most, but obviously required a lot of thinking. I think the countries came out looking very accurate. And even though you say the layers weren’t perfect, I’m sure inside the earth that they aren’t perfectly smooth spheres. 😉

  5. This is beautiful.

    I would have the north pole at the top though personally, since the reason for it showing up on maps and satellites the other way around, is because of the way the planet actually sits, it’s not really anything to do with having America showing for me. I might try this with other planets, or the moon!

    You did a great job.

    • The way the planet actually sits? There’s no difference to the planet between the south and north poles. It’s purely a human convention that the north pole is the one we put on top.

      • Ah bias…

        Don’t you just love it when unconscious bias rears it’s little head.

        Truly lovely cake. I’m a bit sad that my part of the planet didn’t make the cut, so to speak, but really gorgeous. I hope it was delicious, too.

  6. I think the continental map is really neat, and not that much off! Might not lead a pilot to the very precise spot but close 🙂

    • Awesome!

      That is so cool! It’s beautiful. The layers are so nicely done, and the colours look great. What’s up with the North though lol! It’s all stretched flat like a map hehe.

      I like the Australia focus too, though I would have made it peach-coloured, rather than green. Can’t wait to see the plan A one, if you do make it! You should get a globe to use for reference next time, so you don’t have to worry about map projections.
      Awesome. Awesome awesome.

      hehe, if you made it for a special party, and there was a celiac there, you could make them a little gluten-free moon cake. To scale of course 😉

      Another annoying thing about accuracy is the actual thickness of the crust. If your cake had a radius of about 20cm, the crust would be 1 mm. That’s not much icing…

  7. Great cake!

    You did a great job with the continents and it was a great idea. I get excited about cakes, and even more excited with cleverness.

  8. I would never eat something so unnatural (I really don’t understand this colourful chemical trend) but I must admit : it looks awesome! Good job!
    (I loved the funny comment about drawing Europe and America ^^)

    • I’d not assume every coloured cake is made with ‘artificial’ colouring. ‘Natural’ food colourings are not only easy to make at home, but readily available to buy commercially.

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  10. How to make the layers???

    This is absolutely stunning! I am so impressed with your ingenuity, and I would love to try a similar one myself. But I am really not clear on how you made the spheres inside the spheres? Was that middle sphere baked in a small bowl first? More explanation would be VERY MUCH appreciated! Please! Thanks! 🙂

    • Re: How to make the layers???

      Thanks. I used different size puddings bowls or hemisphere cake tins. I’ve not included a recipe yet as the method was not entirely successful (gaps and patches of undercooked batter for present) so I’d rather perfect it myself before sharing a technique that may lead others to disaster.

  11. This is wonderful! I’m thinking of trying it as an ice cream cake, by packing softened ice cream in layers into a round mold, using a different ice cream flavor/color for each layer. Freeze it hard and decorate it fast!!

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  13. What an incredible cake! I’m going to try making one for my dad’s 60th this week. You mentioned another (more ideal) method of baking this cake. What was it? I’m about to buy the equipment so I can go for something specialised. Your cake is inspirational 🙂

    • I find it really difficult to explain via text, especially when I am still experimenting myself! I’m currently working on getting a tute done for this cake to hopefully help with that.

  14. Simply AMAZING! SO impressed with this! Thank you so much for sharing your experiences! Can’t wait for the tutorial! So wonderful of you to be willing to share it with all of us! And from the USA, we don’t mind not being the center of attention when the results are this beautiful! 😉

  15. I did the same thing 25 years ago, but I made mine for my 8th grade earth science class-to illistrate the whole in the OZONE. Mostly I wanted to eat cake in science class (as did my classmates). Who knew it was such a good idea. Yours is way better. I do recall that everyone in class had blue lips!

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  17. Beautiful job! As a science teacher in Ohio, I once did a lesson on the Cincinnati Arches using different colored layers of cake. The bending and folding were not as difficult as I thought they would be, and it really got the point across. So much simpler than your amazing hemisphere project! Kudos.

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    • It’s not difficult to find oven-safe bowls – many ceramic bowls are fired in a kiln that reaches temperatures far beyond the home oven. Many homeware stores also sell pudding bowls that are designed for baking.

    • Kids seldom do, but that’s what I love about them. They don’t care, they just see cake and want to devour it. They ooh and ahh and all that, but they don’t take the time to study the little details. While the adults hesitate and don’t want to touch it, the kids are just waiting for the slightest hint that they are permitted to swam in and destroy it, which they promptly do. Seeing my creations be so fiercely enjoyed is such a wonderful moment for me.

  21. Pingback: Spherical Concentric Layer Cake Tutorial | Cakecrumbs

  22. I don’t understand… did you bake the cake inside a glass bowl? and the inner hemisphere… was that an already baked cake that you then pressed down into the batter of the next layer…but again, within a glass bowl? And did you use a hemispherical cake form for the original smallest hemisphere? Are you willing to share?

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  24. Hi there! My best friend had challenged me to make the most complicated cake that I could for his birthday. A couple of weeks later my cousin shared your earth structural cake on Facebook and I knew that I found my inspiration! The only thing is that I wanted to have filling in between the layers (I’m not a big fan of solid cake). I actually came up with an idea for my own mold using different size hemisphere tins to create hemispheres in layers without carving and allow me to place the them on top of each other. It took me a couple of tries, but I got it to work. It wasn’t as gorgeous as yours, but I accomplished what I wanted and it was a big hit. It was such a big hit that a couple of people who had the cake actually sent me the link back to your blog when they saw it on Facebook later. Thanks for the inspiration!

    Core – White chocolate mousse with mini chocolate chips
    Lower Mantle – Chocolate cake and dulce de leche
    Upper Mantle – Vanilla and chocolate swirl butter cake
    Crust – Buttercream
    Surface – Marshmallow Fondant

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  26. Could you post the recipes that you used, I want to cry and re-create this cake for my 18th birthday (I’m a geography student), this cake is literally amazing!

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