Galaxy Geode Cake Layers:
4 7/8 cups all-purpose flour
4 ½ cups granulated sugar
3 3/4 t. baking powder
1 ½ teaspoon salt
1 ½ cup unsalted butter (or 3 sticks), room temperature
2 ½ t. clear vanilla extract
1 ½ c egg whites (about 12 eggs, or use egg whites from a carton to avoid wasting the yolks)
1 cup buttermilk, room temperature (or buttermilk powder with water is an option if you can’t find liquid buttermilk at your grocery store!)
1/3 cup each Malibu Coconut Rum, blue Curacao, and grenadine
1/8 cup (28 grams) vegetable oil
Reserve & add later -
1-2 small drops teal, blue, pink, and purple gel food coloring, if desired
Mix together all dry ingredients (flour, baking powder, sugar, 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 and vanilla extract on a low speed. Add in and oil, and mix at 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 – I ended up with about 690g 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 35-37 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, 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.
While you’re waiting…make your frosting!
12 oz (one and a half packages) cream cheese, softened
24 Tablespoons (three sticks) butter, softened
10 c powdered sugar
1 T clear vanilla extract
1/4 t. salt (if using unsalted butter)
3-5 T whipping/heavy cream
2-3 drops black gel food color
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.
Optional but recommended:
- Tablespoon or jigger (I used a 45/30mL jigger from my new Nau mixology set)
- additional 1/3 cup each grenadine, blue curacao, and coconut rum
- basting brush or squeeze bottle
- 1 8- or 10 -inch cardboard cake circle (I prefer Wilton’s center-punched circles) and 1 six-inch cake board – one option is to buy a set like this one that contains a variety of cake circle sizes and trimmable dowels
- Ruler (for spacing your dowels and ensuring your tiers stack evenly)
- small paring knife (for making the ‘geode’ cut into the cake)
- Scissors (heavy enough to cut a cardboard cake circle) or kitchen shears
- Small offset spatula
- Airbrush kit (I used this airbrush kit, which is an AMAZING beginner set available on Amazon! +edible airbrush colors (I used this Chefmaster color kit)
- (OR you can use blue, purple, black, and silver edible cake sprays!)
- small new or food-safe paintbrush
- Cake leveler, cake turntable, large offset spatula, and pastry cutter/bench scraper - not all 100% necessary but incredibly helpful! (Here’s a link to the cake turntable I use)
- Silver lustre dust or edible paint
- Rock candy crystals (- I also found a pair of tweezers handy for placing rock candy into the ‘geode’ base)
- (I also purchased some silver rock candy for the cake bases)
- Edible silver leaf (I bought mine from Gold Leaf Factory via Amazon!)
- Silver sprinkle mix (if you want to add sprinkle ‘stars’ to the cake)
Once your cakes are cool, level them (if needed/desired; these cakes usually bake fairly flat so I didn’t trim much from the tops). This can be done with a cake leveler or a large serrated knife and a ruler. (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 recommended!)
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 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 spatulaand 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!
Okaaaay. 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 crush 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! Since I was centering a 6-inch cake on top of an 8-inch cake, I pushed the straws 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 found that my cardboard cake circle showed more than I was happy with, so I piped some extra frosting onto the base of the top tier to hold the rock candy to hide it.
Creating the 'geode:'
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!
With a small offset spatula, re-crumb-coat the geode ‘hole.’ This will keep crumbs in and hold your rock candy in place.
NOW the MOST fun part! Airbrushing!
I used this airbrush kit (surprisingly inexpensive; it’s a GREAT airbrush kit for a beginner!) Quick tip; metallic colors are grainier in consistency than plain colors, and have a bit more of a propensity to clog your airbrush. You may have to pause and clean the airbrush tip a couple times in the process, but it was SO FUN! Highly recommend.
Let each color dry 5+ minutes between coats if you’ve put a lot of color on; too much and it will run in drips and ruin your ‘galaxy’ look!
Once your cake is airbrushed, 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 mix a bit of blue and purple gel color with a bit of coconut rum (so it dries more quickly) and brush into the center/deepest part of the geode. Add a lot of color at the center and make it progressively lighter toward the outer edges. With some lustre dust + rum or edible silver paint, cover the outer edge of the geode, brushing it in toward the center a bit if you’d like.
Rim the outside of the geode with bits of edible silver leaf – I tried a few methods for transferring it, because it’s VERY fragile and a bit 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! 😉