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.
Tried this for my niece’s birthday and it came out great! Thank you!!!
Yay, Meagan! So happy to hear the cake was a hit and happy birthday to your niece!
Hi there! Attempting this today/today for my son’s 1st birthday (and first cake ever too!). I’ve made the 1.5 batches of buttercream frosting in advance however, did you use some of that 1.5 batches to crumb coat your cake too? I’m nervous that if I crumb coat using some of the 1.5 batches, I won’t have enough left for the cake itself. If the 1.5 batches did NOT include the crumb coating, would I be able to use another frosting rather than having to make more buttercream?
Hi Rochelle! So excited for you to make your very first cake and celebrate your son! I started with a chilled and crumb coated cake for this tutorial, but you should have enough for a crumb coat within the 1.5 batches of vanilla buttercream. If you’re super worried about it feel free to use a different frosting for the crumb coat, chill the cake, and use the vanilla buttercream as the tutorial instructs. Hope that helps!
Curious is that 3 layers of a 6 inch cake pan?
Thanks
Hi Coreen! Yes, it is three 6-inch layers.
This may sound silly, but it looks like this has many layers of cake? How many 6 inch round cakes are needed?
Hi Anna! This cake has three 6-inch layers
Could I do the coloured buttercream on top of a black fondant base?
You certainly could, Katie!
Can I use your white chocolate frosting recipe instead of buttercream to make this galaxy decorative cake? Can’t wait to try it!
Hi Stephanie! You can totally use the white chocolate buttercream recipe with this tutorial.
I don’t really care for the sweetness of Buttercream can I use the same method with Swiss Meringue frosting?
Hi Ghazala! This method will work with swiss meringue just fine, as long as you can achieve those deep colors.
I used chocolate cream cheese buttercream. Not as sweet and easy to colour it black.
This was my first attempt at this cake. I made it for my grandson’s Star Wars party. It turned out really well! When you mess up, easy to fix! Thanks for the tutorial!
I am so happy this tutorial was helpful, Rebecca! I bet your grandson loved it!!
My first galaxy cake and I was pleased with the results. Once I got the hang of it, it went pretty well. The nice thing about this cake is, if you mess up, it’s easy to fix.
Yay, Rebecca! So happy this tutorial was helpful!
Hi! I am going to be attempting this cake for my stepson’s birthday, and I had a question! I am going to make the cake with the crumb coating the day before I do the icing. About how much of the 1.5x icing recipe goes toward the colored icing? Thanks!
Hi Jenna! The 1.5x buttercream recipe makes about 4.5 cups of frosting, and about 1.5 Cups of that goes toward the colored icing. Hope that helps!
I kinda just ended up guesstimating, and it worked out! For this being my first really big decorated cake (I know, probably could have started with something a little simpler ), I’m pretty pleased with how it turned out! Thank you!
So happy to hear that it worked out!!
This is a lovely tutorial. I wanted to get your thoughts on modifying this for a cookie cake. My daughter wants a galaxy cookie cake for her 9th birthday.
A cookie cake sounds so tasty, Valyncia! I have never decorated one before, but if you’re wanting flat icing on top of the cookie you can use this same technique where you smooth the colors onto the cookie first, then put some black icing over the top and smooth it all down to reveal some of the colors showing through (then splatter paint for the stars, etc). Since it’s a flat surface you can use an offset spatula for the whole thing and it really helps to have a turntable to spin the cookie cake while you’re smoothing. Hope that helps!
Thank you so much for sharing!
I got some tips on how to splatter the buttercream. Great idea!
Yay! Excited for you to try the splatter technique, Carolina!
Hi, am hoping to make this for a friend’s daughter so had a little go at watering down the buttercream to ‘splatter’ with the brush, did not work at all! Buttercream wouldn’t thin, just went lumpy and horrid. What did I do wrong? Thanks.
Hi Paula, buttercream should always thin when liquid is added. When I thin the buttercream for splattering this way, there are some small lumps in the buttercream and it’s almost the consistency of a thin yogurt. I would add room temp water or milk until you achieve that consistency, then try splattering on a small plate to test the consistency. If you need it thinner, keep adding liquid a little at a time. If it’s too thin, add more buttercream and stir. As an alternative, I’ve also had great success splattering with this Americolor Bright White color gel: https://amzn.to/2uo2ilp
Thanks so much for replying, I’ve had another go this morning using slightly warm water and it was fine. I used cold before (didn’t give it a thought!), so perhaps that is what made the difference. Tested on black card and flicked really well. Thanks again, Paula.
Yay, Paula! So happy to hear that it worked with warmer water! The butter in the buttercream tends to curdle when cold liquid is added so that must have been it.
Thanks so much for the tutorial. I’ve just made a fabulous galaxy cake for my daughter’s 7th birthday. I used navy and black icing on top of purple, turquoise and fuchsia. And then some pearlescent paint and edible glitter sprinkled. It’s so beautiful and I wouldn’t have had the first clue without your fab tutorial. Thank you!
Yay! Glad the tutorial helped and I’m so happy you were able to make such a beautiful galaxy cake for your daughter!
Thank you very much for your video and detailed instructions about how to make the Galaxy cake. I gave it a go and it worked beautifully the first time. It’s wonderful that you’re willing to share your skills and knowledge so that other Cakers could improve as well, thank you once again. I’ve tagged you on Instagram
Hi Sophia! I’m so happy the tutorial was helpful and your galaxy cake turned out beautifully! So excited to check it out on Instagram 🙂