Galaxy Cake Tutorial

galaxy cake tutorial by Sugar and Sparrow

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:

buttercream galaxy cake tutorial

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!

space cake by sugar and sparrow

This Galaxy Cake all starts with a watercolor buttercream technique in a spacey colored palette: pink, blue, purple, and black. I used the Wilton Color Right Food Coloring System for each of the colors, and found it really easy to make a pitch black buttercream with the concentrated gel. It helps that you (surprisingly!) only need a little bit of black buttercream for this project, so if you’ve ever struggled with making a deep black color with vanilla buttercream, you won’t have to worry about that this time around. Just a few drops of black gel added to about ½ cup of vanilla buttercream and you’re good to go! 

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!

buttercream galaxy cake
black buttercream galaxy cake

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:

You Will Need:

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.

how to frost a smooth buttercream cake

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.

frosting smooth buttercream sides
sharp buttercream 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. Add about a Tbsp of white buttercream into one bowl and set it aside, then divide the remaining buttercream into four separate bowls.

buttercream colors for galaxy cake

Using the Wilton Color Right Food Coloring System, mix a little Pink into one bowl, a little Blue into another, and a mixture of Pink and Blue into the third bowl to make a purple tone. In the last bowl, add a few drops of Black 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.

watercolor buttercream tutorial
watercolor buttercream pink

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.

galaxy cake buttercream tutorial

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.

how to make a galaxy cake
how to make a buttercream galaxy cake
how to frost a galaxy cake

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 the bowl of white buttercream you reserved in Step 2, add a few drops of water and mix it all together until it becomes a thick liquid.

splatter painted galaxy cake

Dip your food grade paintbrush into the diluted buttercream and 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.

adding sprinkle stars to galaxy 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!

galaxy cake with stars
galaxy cake finish with silver star sprinkles

Now that you know how to make the perfect Galaxy Cake, all that’s left to do is make a trip to your local JOANN store and pick up the supplies. If you don’t live near a JOANN, fear not! You’ll find everything you need on their website. I’m so blown away at all the cake decorating tools and supplies they offer, so no matter what you’re creating in the kitchen, know that they’ve got just the thing.  

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.


  1. 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 🙂

  2. Ms Megibson

    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!

  3. 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:

      • Paula Harding

        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.

  4. Thank you so much for sharing!
    I got some tips on how to splatter the buttercream. Great idea!

  5. Valyncia

    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!

  6. 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!

  7. Rebecca

    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.

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