Galaxy Geode Cake
Grab some edible cake spray (or an airbrush if you're feeling fancy)! Here's the recipe you need to make a showstopping Galaxy Geode Cake!
Servings: 24 servings
Calories: 755kcal
Equipment
- 1 6 inch cardboard cake circle (I prefer Wilton's center-punched circles)
- 1 Squeeze bottle (optional; I used this to infuse my cake layers)
- Ruler (for stacking cake tiers)
- 1 Small paring knife (to cut out the geode shape)
- Scissors (to cut away a bit of the cake circle inside the geode)
- Airbrush + color kit (or edible colored sprays) (you'll see an airbrush in the video, but you can also use blue, purple, black, and silver edible color sprays!)
- 1 new or food-safe paintbrush
Ingredients
Galaxy Geode Cake layers
- 4 ⅞ cups all-purpose flour
- 4 ½ cups granulated sugar
- 3 ¾ teaspoons baking powder
- 1 ½ teaspoon salt
- 1 ½ cups unsalted butter (or 3 sticks, room temperature)
- 1 ½ cups egg whites (about 11 eggs, or use egg whites from a carton to avoid wasting the yolks)
- 1 cup buttermilk (room temperature)
- 1/3 cup Malibu Coconut Rum
- 1/3 cup blue Curacao
- 1/3 cup grenadine
- 2 ½ teaspoons clear vanilla extract
- 1/8 cup 28 grams vegetable oil
- 1-2 drops teal gel food coloring (optional; add at end)
- 1-2 drops Blue gel food coloring (optional; add at end)
- 1-2 drops soft pink gel food coloring (optional; add at end)
- 1-2 drops Purple gel food coloring (optional; add at end)
Cream Cheese Buttercream frosting
- 12 oz cream cheese (1 1/2 packages; softened)
- 1 ½ cup three sticks butter, softened (3 sticks, softened)
- 9 cups powdered sugar
- 1 Tablespoon clear vanilla extract
- ¼ teaspoon salt if using unsalted butter
- 3-5 Tablespoons whipping/heavy cream
- 2-3 drops black gel food color
Cake drizzle (optional)
- 1/3 cup Malibu Coconut Rum
- 1/3 cup blue Curacao
- 1/3 cup grenadine
Decorations
- Rock candy crystals (I also found a pair of tweezers handy for placing rock candy into the ‘geode’ base)
- Edible silver leaf (I bought mine from Gold Leaf Factory via Amazon)
- Silver sprinkle mix (optional; to add sprinkle ‘stars’ to the cake)
Instructions
Cake layers
- Preheat oven to 350°F. Prepare three 8-inch cake pans and two six-inch cake pans with baker’s floured cooking 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 bits 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 egg whites and mix on low until just incorporated. Mix in the buttermilk, rum, blue curacao, and grenadine on a low speed. Add in vanilla and oil, and mix on low 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 – I had 675g in my large pans and about 450 in my smaller ones). This guarantees your layers will bake to be the same height.
- Time to add in the colors! With a toothpick, skewer, or butter knife, add a drop of two of each gel color to each cake pan, and swirl them together with a butter knife.
- 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. Place cake layers into the freezer for 45 minutes, to accelerate the cooling process.
- Once the layers have fully cooled, they can be leveled and any 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. (This is a great time to make your frosting!)
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, gel color, and salt if needed and beat until well combined.
Assembly
- (I wanted a bit more liqueur kick to my cake layers, so I used a squeeze bottle to infuse each one with a few tablespoons of the rum/curacao/grenadine mix above. Optional but delicious! ;) )
- 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). Add your next cake layer on top, and repeat the process with your remaining cake layers.
- Next, repeat the same process with your smaller cardboard circle and cake layers. Of note – if your circles aren’t pre-center-punched, be sure to grab a dowel or straw and make your own hole in the exact center of the circle! This will allow you to easily center the tier on the base tier later on.
- 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 layers of frosting and smooth. I like to use a large offset spatula and pastry cutter/bench scraper for this part.
- (For my larger tier, I was able to smooth the frosting fairly well free-handed, but I struggled getting the sides smoothed on my smaller one. Trimming the layers just smaller than the cake circle and using the cardboard as a guide for my bench scraper worked well for smoothing the frosting on the top tier!)
Okaaay. The stacking process!
- ‘How to Make a Tiered Cake’ by Chelsweets is still my favorite video tutorial to date – sometimes seeing the process can be very helpful!
- Basically, doweling a tiered cake is done to ensure that the top tier doesn’t sink into the lower tier, as well as keeping it centered. I used four shorter cut-to-height plastic straws for my base tier dowels, and one taller one cut at an angle in the center to hold my top tier in place.
- Grab your ruler for this next part! Push the straws/dowels (cut to the height of the cake) down into the base tier just over one inch from the cake edge, placing them evenly at quarter intervals around the cake. Place your last, tallest straw or dowel into the exact center of the cake, making sure to keep it straight up as you press down. Now you’re ready – center the hole in the bottom of your top tier cake circle over the tallest dowel and let the top tier gently down onto the base tier. The dowel will poke into the center of the top tier to hold it in place.
- (I could still see my cardboard cake circle a bit, so I covered it up with some rock candy.)
Cutting the geode
- Cut a slanted geode shape out of the side of the cake - I shot for about 1” from the top and 1” from the cake base for the ends, and made two cuts connecting my end points. I made the opening deepest toward the center, probably 1 ½” at its deepest. (Feel free to eat the cake scraps!) I had to use a pair of scissors to cut out a bit of the 6" cake circle too.
- With an offset spatula, re-crumb-coat the geode ‘hole.’ (This will keep crumbs in and later hold your rock candy in place.)
Now the most fun part! The galaxy colors!
- (I used this airbrush kit (surprisingly inexpensive; it’s a great airbrush kit for a beginner) but it's quicker and less expensive to use edible cake sprays.)
- Spray colors onto the side of the cake - I started with blue, then purple, then black, and finished with silver. Let each color dry 5+ minutes between coats if you’ve put a lot of color on; too much and it will drip and ruin your ‘galaxy’ look!
Finishing the geode
- Once your cake is colored, press rock candy crystals into the frosting to cover the base of the geode ‘hole.’ I found tweezers handy for reaching the deeper parts.
- To color the geode, use a bit of airbrush color or dispense some cake spray into a small bowl and brush into the center/deepest part of the geode. Add the most color at the center and make it progressively lighter toward the outer edges. I added more silver with a brush along the outer edge.
- Rim the outside of the geode with bits of edible silver leaf – I tried a few methods for transferring it, because it’s a bit fragile and finicky. Tearing off and moving bits at a time with a paintbrush has been my favorite method so far!
- With your paintbrush and a bit of metallic silver paint or lustre dust, add a few ‘flicks’ of silver spray onto the cake. Finish it off with a few silver sprinkle constellations and some silver rock candy around the tier bases – and you’re done!
- Seriously; find someone to give you a high-five on your kick-butt cake! 😉
Video
Notes
Small paring knife (to make the geode cut in the side of the cake
5 large straws or cake dowels
OR you can use blue, purple, black, and silver edible cake sprays!
5 large straws or cake dowels
OR you can use blue, purple, black, and silver edible cake sprays!
Nutrition
Serving: 1slice (1/24th cake) | Calories: 755kcal | Carbohydrates: 98g | Protein: 8g | Fat: 37g
Did you make this Galaxy Geode Cake?
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