Galaxy Cake Tutorial

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:

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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.