Jun 102017
Geology Themed Chocolate Birthday Cake

I’m still horribly jet lagged after returning to the UK on Wednesday, hence why this post is a day late. Last night I finally managed to sleep through until 7am (sadly Lucy didn’t), but we’re both exhausted. Yesterday, Lucy went to work and I set up camp on the sofa. Around 3pm I decided I’d rest my eyes for a few minutes while bingeing on 24 Hours in A&E, but at about 4pm Lucy came home early and shouted “hello”. In my sleep-deprived and delusional state I thought the people on the t.v. were talking to me and decided to answer them back… confused as to why the trauma patients were in my living room. In any case, I’m back and things are returning to normal after our holiday, except that my posting schedule will be changing to Saturdays due to my new work schedule (more on this later). Now on to the geology themed chocolate birthday cake!

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Geology Themed Chocolate Birthday Cake

Why Geology Themed?

I come from a family of scientists (and I’m convinced I’m not related). My mom is in earth sciences, and my brother is working on a BSc in earth sciences. When I found out that my friend Hayley’s wedding and our holiday was at the same time as my brother’s birthday, I started planning ideas for a cake. I can’t even remember the last time I was in Vancouver for his birthday!

Geology Themed Chocolate Birthday Cake

Planning the Cake

After nosing around on Pinterest, I decided that a ‘geology themed’ cake would be perfect. I found a great picture of a cake with striations (rock layers) and an aquifer, and was determined to duplicate it. I opted for a devil’s food chocolate cake base to get the height I needed for the layers, but without it being stodgy, and a pale chocolate buttercream with smashed chocolate wafer cookies (like Oreos without the filling) for ‘soil’ texture. I also ordered some chocolate pebbles off of Amazon and brought them over from the UK. The layers of soil are made from crushed chocolate wafers, and ground graham crackers. The aquifer (totally inaccurate says mom, the hydrogeolgist) is made from white cake gel and blue glitter sprinkles (which I pressed on with my fingers while very hung over). So, think of this cake as an artist’s interpretation of ‘science’.

While we were in Fort Langley, we went to a candy store and I found those awful crystal rock candies on a stick and bought two to make crystal/gem veins. From there, Lucy and I hunted through our Lego collection to find anything suitable to be ‘miners’ (and washed them). Unfortunately, we had no Lego earth sciences collections, but we managed to find some scuba men, knives, walkie talkies, and medieval swords… And this is my masterpiece! P.S. My brother took some leftovers to the other students and they approved of my scientific culinary wonder.

Geology Themed Chocolate Birthday Cake

The cake recipe comes from Life Made Sweeter, and was absolutely delicious! I like that devil’s food cake has a bitter chocolate taste and is not too heavy, which helped balance out the crap-load of sugar in the frosting and decorations. Note that the recipe below is for three 6 inch layers or two 8 inch layers. I multiplied the recipe by 1.5 to get three 9 inch layers, so feel free to also make those tricky math conversions if you want to try making this three-layer monster.


Chocolate Cake Recipe

1 3/4 cups flour
1 3/4 cups sugar
3/4 cup unsweetened cocoa powder
2 tsp. baking powder
1 tsp. baking soda
1/4 tsp. salt
2 large eggs, room temp.
3/4 cup buttermilk, room temp.
1/4 cup light sour cream, room temp.
1/3 cup vegetable oil
2 tsp. vanilla extract
3/4 cup boiling water


Preheat the oven to 350F and prepare three 6 inch or two 8 inch (note I multiplied the recipe by 1.5 for three 9 inch layers) round cake pans and spray them with baking spray (I rubbed butter). Dust with cocoa powder and a bit of flour and shake out the excess.

Combine the flour, sugar, cocoa powder, baking powder, baking soda, and salt in a large bowl with a wooden spoon (or in your stand mixer).

Add the eggs, buttermilk, sour cream, oil, and vanilla. Beat with an electric mixer on medium speed for about 2 minutes until smooth.

Reduce the speed and slowly add the boiling water to the batter. Turn the mixer to high and beat for a further minute.

Divide the batter between the pans and bake for 30-35 min (I baked 30 min on 360F because my parents’ oven is stupid). Test with a toothpick.

Chocolate Cake

Remove from the oven and allow to cool for 15-20 minutes before inverting onto racks to cool completely before icing.

Geology Themed Chocolate Birthday Cake


1 1/2 cups (3 sticks) unsalted butter, room temp.
4-5 cups icing sugar, sifted
1/2 cup cocoa powder, sifted
4 tbsp. whipping cream
2 tsp. vanilla
1/8 tsp. salt
1/2 pack chocolate wafers (crushed in a bag with a rolling pin, or in a food processor)


Beat the butter with an electric mixer on high until light and creamy, about 5 minutes. Turn to low speed and slowly add the cocoa powder, and sifted icing sugar, 1 cup at a time. On medium speed, add the vanilla and cream. Switch to high speed for 1 minute and beat until smooth. Adjust the cream or sugar as needed for consistency. Mix in the chocolate wafer crumbs.


I should note that I used this quantity of icing which is intended for a smaller cake on my 1.5X larger cake and it was just enough. My family actually doesn’t like sweets that much (so obviously I had to punish them with this sugar demon), so less icing is better. This icing was very tricky to frost with because of the lumps, but I managed it with a spatula and butter knife. The good thing is that it is meant to be soil, so it’s allowed to be uneven!

If you try out this recipe, let me know! I hope you’ve enjoyed this fun geology themed chocolate birthday cake!

For more birthday cake ideas see: Honey Butter Birthday Cake and Lemon Buttermilk Birthday Cake

Icing the cake

Geology Themed Chocolate Birthday Cake

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