The endlessly-trending geode cake! 😉
First – quick story (read: cautionary tale :cough:)
Several years ago, I tried as a (clueless) newbie baker to make a geode cake.
I apparently thought just adding food color to rock candy crystals and placing them onto the cake would work… (?) If you’re thinking ‘that doesn’t sound like a great idea’ you’re 100% correct. I’m not quite sure where I got this idea. But it didn’t work out well and I definitely don’t recommend it!
I finally found a picture – and you can see for yourself, the result was far from beautiful. Actually – it looked looked kinda awful. See below. I’m not joking. Or even exaggerating.
So – all of that said – if you’re reading this post with plans to make a geode cake – you’re you’re already way ahead of me! 😉
Learn from my mistakes and color the rock candy AFTER you put it on the cake!
Why make a geode cake?
Geode cakes are beautiful! They’re fascinatingly unique and really a fun decorating project. Geode cakes feature a beautiful a stunning crystal-like design made with rock candy (or isomalt sugar). Every one is as unique as a real geode, and they are so fun to decorate!
The distinctive geode shape and design is made by –
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cutting a geode shape out of a frosted cake
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coating the inside of the geode with frosting (to adhere the rock candy)
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placing rock candy inside the geode, covering the inside of the cavity
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using food coloring to add color and depth to the geode shape!
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Adding any extra decorations to the outside of the geode and the rest of the cake! You can use decorations like gold or silver leaf, edible paint, or food-safe flowers.
“Can I use a different cake or frosting recipe?”
- Absolutely! I’ll just make a couple of quick recommendations –
- I’d recommend picking a cake recipe that’s not too crumbly. Cutting out the geode shape and re-frosting that spot can be a bit of a bugger. It’ll be harder if you have cake layers that are really soft or crumble easily.
- I’d also recommend going with a frosting recipe / color that’s going to give you a good amount of contrast with your geode color.
Annd….I think that covers everything I have to tell you! On to the recipe!
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Geode Cake
Equipment
- Small paring knife (to cut out geode shape)
- small offset spatula ( to fill geode shape)
- Small new or food-safe paintbrush
Ingredients
Geode Cake Layers
- 3 ¼ cup all-purpose flour
- 3 cup granulated sugar
- 2 ½ teaspoon baking powder
- 1 teaspoon salt
- 1 cup unsalted butter or 2 sticks room temperature
- 1 ½ cups buttermilk room temperature
- 5 eggs
- 2 teaspoons clear vanilla extract
Cream Cheese Buttercream Frosting
- 8 ounces cream cheese one package; softened
- 1 cup butter two sticks, softened
- 6 cups powdered sugar
- 2-4 Tablespoons milk
- 1 Tablespoon clear vanilla extract
- ¼ teaspoon salt if using unsalted butter
- 3-4 drops teal gel food coloring optional; save and add later for cake filling
Geode / Decorations
- 1 package Rock candy crystals (you may find tweezers helpful if decorating a very narrow geode shape)
- 3-4 drops teal gel food coloring
- 3-4 drops clear vanilla extract (to fade the color toward the outside of the geode; vanilla dries faster than water)
- Edible silver leaf
- Silk or food-safe flowers (optional)
Instructions
Geode Cake Layers
- Preheat oven to 350°F. Prepare three 8 inch round pans with baker’s floured spray (or grease and line with parchment rounds).
- Mix together all dry ingredients (flour, sugar, baking powder, and salt) in a stand mixer with a paddle until fully combined. Mix chunks of room-temperature butter slowly into the dry mix, on a low speed. Continue to mix until no large chunks of butter remain, and the mixture becomes crumbly.
- Pour in eggs and mix on low until just incorporated. Mix in the buttermilk and vanilla on a low speed until fully incorporated. Scrape down the sides of the bowl with a spatula, then beat on medium speed for about 30 seconds.
- Divide batter evenly between the prepared cake pans (I find a kitchen scale helpful for this part). This guarantees your layers will bake to be the same height.
- Bake for 34-37 minutes (or until a toothpick comes out clean). Allow cake layers to cool for 10-15 minutes on a wire cooling rack before removing from pans. Cool completely before frosting. Set in the fridge or freezer to accelerate the cooling process if desired. (This is a great time to make your frosting!)
- Once the layers have fully cooled, the caramelized bits can be trimmed from the sides / top of the cake using a serrated knife if desired. Be sure the layers are completely cooled or chilled before trimming. If you try to trim the layers while they’re still warm, they will crumble apart.
Cream Cheese Buttercream Frosting
- Beat together softened cream cheese and butter; slowly add in powdered sugar alternating with milk until frosting reaches desired consistency. Add vanilla and salt if needed and beat until well combined.
Assembly
- Once your cakes are cool, level them (if needed) Place a smear of frosting on your large cake circle (to keep the cake from sliding while you decorate it) and center your large first cake layer in the center of the circle. Spread the layer with frosting, or add a small ‘rim’ of white frosting and fill with teal frosting. Add your next cake layer on top, and repeat the process with your remaining cake layers.
- Now you’re ready to crumb-coat . If you’re unfamiliar with crumb-coating, it’s just what it sounds like – spreading a thin layer of frosting over the entire outside of the cake tiers to keep crumbs out of your final layer.
- Once your crumb coat has set (this takes about 5-10 minutes in the fridge), add your final layer of frosting and smooth. I like to use a large offset spatula and pastry cutter/bench scraper for this part.
- Now the FUN part! Carve your ‘geode’ shape! Cut an irregular shape out of the side of the cake – I shot for a few inches across at the widest point, but you can make the geode as wide or narrow as you choose.
- With a small offset spatula, re-crumb-coat the geode ‘hole.’ This will keep crumbs in and hold your rock candy in place.
- Press rock candy crystals into the frosting to cover the base of the geode ‘hole.’ (If your geode is very narrow, tweezers may help to place candy in the deepest parts.)
- To color the geode, use a bit of teal gel color with a bit of vanilla extract (so it dries more quickly) and brush into the center/deepest part of the geode. Add a lot of color at the center and continue to thin the color with vanilla extract to make it progressively lighter toward the outer edges.
- Rim the outside of the geode with bits of edible silver leaf – I tried a few methods for transferring it, because it’s fragile and a bit finicky. Tearing off and moving bits at a time with a dry paintbrush has been my favorite method so far!
- Finish it off with a few extra pieces of silver leaf and some silk flowers if you’d like – and you’re done!
Video
Notes
Nutrition
Mentioned in post –
Cream Cheese Buttercream Frosting
Did you make a Geode cake, or have any comments or questions?
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