If you were offered a ticket to space, would you go? I totally would (even though I’d be terrified) because I have always been captivated by all things space. The planets, the stars, the crazy colors, the final frontier – it would all be worth floating around in a spaceship and eating weird food just so I could see it all up close! So far, the closest I can get is channeling my love for space into an out of this world Galaxy Cake!
Cool, right?! Whether you’re needing a buttercream backdrop for your next Star Wars cake or other space-themed creation, this technique was so quick and easy with a few supplies I picked up at my local JOANN store. From the space-colored buttercream to the star textures and sprinkle accents, I found everything I needed to get the look in a one-stop shop!
UPDATE 2025: JOANN has (sadly!!) gone out of business, so I have slightly changed these product links.
This Galaxy Cake all starts with a watercolor buttercream technique in a spacey colored palette: pink, blue, purple, and black. I first frost the pink, blue, and purple colors before adding the black over the top, which makes it so that you (surprisingly!) don’t need to use a lot of black frosting. In fact, it’s only about 1/2 Cup of black frosting that you can make with either a few drops of black food color gel or black cocoa powder if you don’t mind a little chocolate flavor.
To really enhance the look of a star-filled galaxy, I splatter painted the cake with diluted vanilla buttercream, added these gorgeous Silver Edible Glitter Stars, and topped it all off with a few clusters of these Silver Sprinkles. It turned out so galactic!
Here’s a quick video of the process so you can see all of the techniques in action before you read all about it below:
If you love tutorial videos like this one, be sure to check out my YouTube channel! I’ve got a growing collection of cake recipes, decorating tutorials, and Cake Basics over there. Hit the subscribe button on my page so you never miss a new video.
You Will Need:
- A 6-inch round cake that’s been crumb coated and chilled
- Cake turntable
- 1.5 batches of vanilla buttercream
- Food color gels in pink, purple, blue, and black (or black cocoa powder)
- Bowls and spoons for color mixing
- Angled Spatula
- Icing Smoother
- Food-Grade Paint Brush
- Wilton Silver Edible Glitter Stars
- Wilton Silver Sprinkles
- AmeriColor Bright White color gel
Step 1: Frost The Cake
With your crumb coated and chilled cake on the turntable, frost a thin layer of vanilla buttercream onto the top of the cake and smooth it down with your angled spatula.
Add a thin layer of vanilla buttercream to the sides of the cake and smooth it with your icing scraper until the sides are smooth and even. Then, swipe the crown of buttercream that appears around the top edges of the cake inward to create sharp edges.
At this point, I like to chill the frosted cake for about 20 minutes to let the buttercream set up. Frosting white buttercream underneath the galaxy finish saves on the amount of black buttercream you’ll need to use to cover it. Aka, no black stained teeth once you get to eat it!
Step 2: Color The Buttercream
While the frosted cake is chilling in the refrigerator, it’s time to mix up your space-themed color palette. Divide the remaining buttercream into four separate bowls.
Using the mix a little pink food color gel into one bowl, a little blue into another, and purple into the third bowl. In the last bowl, add a few drops of black food color gel or black cocoa powder and mix it up until you’ve got a deep black tone.
Step 3: Create The Galaxy Buttercream Finish
On your frosted and chilled cake, add a few dabs of the pink buttercream to the sides and top of the cake with your angled spatula, then smooth it all with your icing scraper.
Next, add a few dabs of purple buttercream to the sides and top of the cake and smooth it with your icing scraper. Repeat this process with the blue buttercream until you’ve got a nice watercolor finish on your cake. No need to refrigerate these colors in between applications – we want them to blend together a little.
Finally, add the black buttercream over the top of everything and smooth it with your icing scraper. Continue to add and smooth the black buttercream until the colors underneath peek through just a little.
When you’re finished, pop the cake back into the refrigerator for another 15 minutes to let everything set up.
Step 4: Splatter Paint The Stars
In a small bowl, add about 1/2 teaspoon of AmeriColor Bright White or other liquid icing whitener. Dip your food grade paintbrush into it and use it to splatter paint it all over the cake to create the look of stars.
Step 5: Add Glitter Stars And Sprinkles
Finally, add some Glitter Stars wherever your heart desires in your galaxy. It’s best to place a few on your finger and gently press them onto the cake. Use that same technique to add some clusters of Silver Sprinkles to your galaxy cake. Simply dip your finger into the sprinkles to get a nice finger-full, then gently press them onto the cake.
And there you have it! When you’re all done with your Galaxy Cake, feel free to turn on “Intergalactic” by Beastie Boys and dance around the kitchen. It’s only fitting!
Disclaimer: I was compensated by JOANN for my work of creating this project, styling, filming, photographing, and writing about their products. As always, all opinions are honest and my own. Thank you for supporting brands that support Sugar & Sparrow.
Thank you so much for your recipes and tutorial. I made this galaxy cake for my son’s 2nd birthday and it came out amazing! Your tutorials for perfect one bowl chocolate cake, vanilla buttercream frosting and decorating the galaxy cake were awesome and so helpful.
Excited to try more of your recipes =]
Yay, Kerry! That makes me so happy to hear!! Thanks so much for taking the time to tell me and I’m so glad your little one loved his cake 🙂
Do you think instead of coloring the frosting, I could paint the black food coloring onto the cake with a brush? I was thinking something similar to when you paint gold edible paint onto cakes.
Hi Michelle! I don’t think that would work because it would a) be a real mess/streaky and b) ruin the flavor of the frosting. Instead, if you’d rather paint on the color I would try this Edible Art Paint: https://amzn.to/3iNLn2z
Hi! I used this tutorial and your chocolate cake to make my son’s first birthday cake. I couldn’t get the black color to come out so it turned out a lot more purple but I’m happy with how it looked. Thanks for the recipes! I’m linking a picture if you’re interested. 🙂 https://i.imgur.com/MCpDprX.jpg
It looks beautiful, Mina! I’m so happy this tutorial was helpful and I think the colors look amazing!
I LOVE how your purple galaxy cake turned out, it’s gorgeous. Purple is my favorite color so I may try doing this cake that way instead of the black.
I never could get my frosting black. It was more a dark gray. The frosting had a strange flavor due to all the black I added. But, otherwise a good cake. The other colors were vibrant and the color chart was very easy to use. My son and I enjoyed decorating his birthday cake. I also love the Vanilla Buttercream Frosting recipe. I have never made a decent tasting vanilla frosting before. Your tutorials seem pretty easy to follow.
Hi there! I’m sorry your frosting ended up tasting weird and didn’t turn completely black. Sometimes it takes awhile (30+ minutes) for the black color to intensify – it starts out a concrete gray color and then deepens. Next time you can also try adding a little bit of cocoa powder to the buttercream you want to tint black, that way you don’t have to add as much (it’s easier to go from brown to black than from white to black). So happy you love the vanilla buttercream recipe!
Hi, This cake looks fab. I am planning on making it for my daughters 2nd birthday and have Enright apart from the gel colors. Apart from the black which specific colors did you use for the pink and blue? I currently have dusky pink, pink and royal blue
Yay, Charlotte! I used the Wilton Color Right Food Coloring System for the pink and blue colors. It’s a set that you use to custom mix colors, and I believe I used the pink + a tiny bit of blue to create a fuchsia color and then just used the blue for the blue color. You can use any pink and blue for those colors though!
Hello! I am very excited to try this for my brother’s 30th birthday surprise space-themed party. However, I have a cake recipe in mind that has a delicious cream cheese frosting I want to use. Do you think that would work okay for this frosting technique? Any tips or things to watch out for?
Thank you! The cake is beautiful!
Hi Claire! Cream cheese frosting should work totally fine with this tutorial! As long as it’s easy to frost a cake with and you’re able to tint it to get the color palette you should be totally good.
Hi Whitney thank you so much for sharing this tutorial. The cake looks amazing my daughter has asked for a galaxy cake for her birthday and I’m really nervous about making it because I don’t have a lot of experience frosting a cake. My frosting always seems a bit stiff for some reason anyway her favourite cake is Chocolate Fudge cake, do you think this would work also? And how much frosting would I need for a 2 layer 8″ cake please?
Thank you so much for your time
Yay, Petra! Excited for you to try this cake for your daughter. Any layer cake recipe will work with this tutorial and I do have my favorite vanilla buttercream recipe here (which is what I use in this tutorial) in case you need one that will frost easily: https://sugarandsparrow.com/vanilla-buttercream-recipe you’ll need to double the recipe if you want to use it as filling as well as frosting, but if you’re just frosting the outside of the cake you can make the recipe as-is. This galaxy technique is super forgiving, so I hope you have fun with it! Enjoy!
Hey Whitney,
Thank you so much for the reply. Oh I will have a look at the vanilla buttercream recipe. I tried the rasberry buttercream on your rasberry chocolate cake at the weekend and it was amazing so can’t wait to try it.
Just out of curiosity could you fill and frost this cake with coloured ganache too? And if so do you have a recipe?
Sorry to bother you again
Thank you
Hi, this looks like a great tutorial. I can’t wait to try it next week for my daughter’s 10th birthday. Would whipped icing work too? Thanks!
Yay, Dominique! Excited for you to make this for your daughter’s birthday! As long as you’re able to achieve the colors with whipped icing and it’s what you would normally frost a cake with, it should work.
I love your cake!! Can you do it with fondant? 🙂
Hi Melody! You could certainly do a galaxy finish with fondant, though the technique will be quite different. I don’t specialize in fondant finishes, so I would look for a galaxy cake tutorial that uses fondant if you want to get the look with it!
Thank you. I used the technique on a half spear cake and it turned out really good and easier than a I thought.
I bet this technique looked amazing on a half sphere cake! What a great idea, Brenda!
Hello! I’m planning to make this cake this weekend for a birthday party. I had planned to use boxed cake mix just to save time on that end, and because, why not, but I’m concerned that it might be too soft of a cake to hold up to the work that the frosting entails. Can you tell me if you know if it needs to be a denser type of cake, such as homemade? Thank you.
Hi Louise! A boxed cake mix is absolutely fine to use with this tutorial. I actually use box mixes quite often when creating decorating tutorials (because making a cake from scratch takes a lot of extra time and ingredients!) and I have not run into any problems with the cake being too soft. Go for it!
Instead of buttercream, would white ganache (with the different colors) work to get a similar effect?
Hi Bhavna! I think you could create this look using ganache that is frosting consistency. I’ve never tried it before, so I’m not entirely sure, but I think it’s worth a try!
I want to make this for my son’s 2nd birthday, but am being warned that the black icing (and any icing that is on the darker side) will stain teeth and have an artificial taste. I know you said that you took steps to avoid that with your process, but how concerned should I really be?
Hi Michelle! Yes, large amounts of black buttercream will temporarily turn your tongue purple. The gel I use to make the black buttercream in this tutorial is tasteless and since you really don’t need to make a lot of black buttercream for this cake, the taste should not be an issue at all. If you are concerned about a temporary purple tongue though, I would look into Black Cocoa Powder for making black buttercream. I’ve never used it before, but I hear it helps make a deep black color without turning mouths purple!
Hello! I want to make a fault line cake with a strip of pictures in the middle. I thought it would be really cool to have galaxy themed buttercream coating the top and bottom rather than a solid colour. I’m not sure if this will make things too complicated (I’m a home baker)
Do you think I should add the coloured buttercream and smooth each colour individually as you’ve done here or will adding the different colours in one go and smoothing it work?
Thank you! Your cake looks amazing.
Hi Rameen! I think a fault line galaxy cake will look AMAZING! If I were doing a cake like that I would add all the vibrant colors in one go and smooth them down first, then add the black on top. You can certainly try adding everything at once but I’m not sure if the colors would get too muddy. I’m excited for you to try this though, tag me on Instagram to show me if you end up making it!
How do you move the cake from the turntable without messing up the frosting?
Hi Jenni! I am actually working on a Cake Basics tutorial on this topic. Basically I heat up an angled spatula and run it around the bottom edge of the cake (make sure the cake is refrigerated for at least 30 min first). Then I slide the spatula underneath the cake and slip my hand under to hold the bottom and transfer it that way. There will be a video to come but I hope that helps in the meantime!