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.

61 Comments

  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: https://amzn.to/2uo2ilp

      • 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.

  8. 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!

  9. Ghazala Malik

    I don’t really care for the sweetness of Buttercream can I use the same method with Swiss Meringue frosting?

  10. Can I use your white chocolate frosting recipe instead of buttercream to make this galaxy decorative cake? Can’t wait to try it!

  11. Anna Parmley

    This may sound silly, but it looks like this has many layers of cake? How many 6 inch round cakes are needed?

  12. […] chocolate birthday cake, so I whipped up my go to recipe, and then tried a cookie dough filling and vanilla frosting. I followed this tutorial to make a galaxy cake, and for a first attempt, decorated in a kitchen […]

  13. 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!

  14. Meagan Payne

    Tried this for my niece’s birthday and it came out great! Thank you!!!

    • 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!

  15. 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!

  16. Michelle Jacobs

    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!

  17. 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!

  18. Louise Bird

    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!

  19. Thank you. I used the technique on a half spear cake and it turned out really good and easier than a I thought.

    • 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!

  20. Dominique

    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.

  21. 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

  22. Claire

    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.

  23. Charlotte earl

    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!

  24. Just Nic

    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!

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