Galaxy Chocolate Cake

Vegan chocolate galaxy cake is a moist chocolate cake with chocolate and vanilla buttercream frosting. The clear instructions with shortcuts make this recipe easy enough for even a non-baker. Make it for an upcoming birthday celebration or another space related occasion.

This recipe makes a 2-layer 8” or 9” round vegan chocolate galaxy birthday cake (12-16 slices).

Table of Contents

(click the links below to skip to the section you’re looking for)

• Galaxy Chocolate Cake Recipe
• Galaxy Buttercream Recipe
• Decorations
• Cake Assembly
• Frequently Asked Questions
• Ingredient Substitutions
• Video
• Comments or Questions
• Other Galaxy Recipes

My first time making a galaxy buttercream cake was in 2018, and it actually turned out good. Back then, mirror glazes were popular for galaxy cakes. Since my cake style is more hodge podge, I worry that if I attempt a mirror glaze for someone’s birthday, it might look like a pinterest fail.

In 2018, Alissa’s birthday party was on May 4 (you know the whole May the 4th Be With You thing). May 4 is also space day, so I felt like this space-themed cake was appropriate. I’m making it again in September 2023 as early vegan birthday cake for Goose. I made a deal with Goose that if they went vegan, I would make them their next 10 birthday desserts, and this is the first one. They requested a galaxy birthday cake because they work at the planetarium doing space shows and space is kind of their thing.

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Ingredients for Vegan Chocolate Cake

(jump to the substitutions section to see ingredient details and suggestions for substitutions)

• 1 ¾ cups (240g) all-purpose unbleached flour
• ¾ cup (55g) cocoa powder
• 1 ½ cups (330g) vegan sugar
• 1 ½ teaspoons (10g) baking soda
• 1 ½ teaspoons (8g) baking powder
• ¼ teaspoon (1g) salt
• ½ cup (120ml/105g) sunflower or safflower oil
• ¾ cup (180g) vegan yogurt
• 1 cup (240ml/235g) nondairy milk
• 1 tablespoon (14g) apple cider vinegar
• 2 teaspoons (8g) vanilla extract
• ½ cup (120ml/118g) hot coffee

How to Make A Galaxy Chocolate Cake

prep time: 15 min | baking time: 30 min

Preheat the oven to 350°F (175°C).

Oil the bottom and sides of two 8-inch or 9-inch round cake pans.

Cut out pieces of parchment paper that are the size and shape of your cake pans, put them in the bottom of your cake pans, and then oil the top of the parchment paper. Parchment paper on the bottom of 8" round cake pans just helps the cake come out of the pans, but you can make this cake (and all my cakes) without parchment paper.

Whisk the wet ingredients either by hand in a large bowl or with a stand mixer fitted with a whisk attachment (or a handheld electric mixer): ½ cup (120ml/105g) oil, ¾ cup (180g) vegan yogurt, 1 ½ cups (330g) sugar, 1 cup (240ml/235g) plant milk, 2 teaspoons (8g) vanilla extract, and ½ cup (120ml/118g) hot coffee.

Sift the dry ingredients into the bowl with the wet ingredients. Your dry ingredients include the following: 1 ¾ cups (240g) flour, ¾ cup (55g) cocoa powder (I use this cocoa powder because it’s fair trade), 1 ½ teaspoons (10g) baking soda, 1 ½ teaspoons (8g) baking powder, and ¼ teaspoon (1g) salt.

Mix until you no longer see any dry ingredients, but don’t continue mixing after that point.

Check to make sure your oven is preheated before continuing to the next step. If it hasn’t reached 340ºF, wait until it gets there before continuing.

Mix in 1 tablespoon (14g) apple cider vinegar gently, but quickly. You want to move quickly because as soon as the vinegar joins the batter, the chemical reaction of the vinegar and baking soda start to work their magic. You want that magic to happen in the oven, not on your kitchen counter.

Divide the batter evenly between your 2 cake pans.

Place the cake pans on the same rack in the oven so that they will all bake at the same temperature. I know this sounds weird, but our ovens are actually different temperatures in different spots.

Bake for 30-35 minutes at 350ºF.

Baking times vary depending on different ovens, so I always set my timer for the lowest baking time, and then check the cake with a toothpick. If the toothpick doesn’t come out clean after poking the middle of the cakes, then I bake them a few more minutes, and continue.

Remove the cakes from the oven as soon as the toothpick test comes out clean, and set them on a cooling rack.

Cool the cakes for 15 minutes before flipping them upside down on the cooling racks. You can start on the frosting while you wait for the cakes to cool completely.

Ingredients for Vegan Galaxy Buttercream Frosting

(jump to the substitutions section to see ingredient details and suggestions for substitutions)

• ¾ cup (132g) vegan butter or margarine *
• ¾ cup (144g) organic palm shortening *
• 2 teaspoons (8g) vanilla extract
• 5 cups (600g) organic powdered sugar *
• Up to 2 tablespoons nondairy creamer or milk (optional, to achieve a creamy consistency if needed)
• vegan food coloring

How to Make Vegan Galaxy Buttercream Frosting

prep time: 30 minutes

Leave the ingredients sitting out before using them. Best results come from using room temperature ingredients.

Whisk ¾ cup (144g) vegan shortening and ¾ cup (132g) vegan butter for 1 minute using a stand mixer or a handheld electric mixer.

Add 2 teaspoons (8g) vanilla extract, and mix for another minute.

Sift in 5 cups (600g) powdered sugar, 1 cup (120g) at a time, mixing for at least minute between each addition.

Scoop a quarter of the frosting into 1 bowl and a quarter in another bowl. Leave half of the frosting in the mixing bowl.

Add 2 tablespoons (12g) of cocoa powder and 2 tablespoons (20g)of black cocoa powder to the mixing bowl.

Mix for a minute or until the frosting turns dark grey.

Add vegan food coloring to the other bowls of frosting, and mix well. You can use any colors you like, but I used wilton sky blue gel color for one bowl and wilton violet gel color for the other. If you prefer all-natural food colors, check out my list of vegan food coloring.

Ingredients for Vegan Asteroids or Planets

• 1 cup (340g) chocolate chip cookie dough
• ½ cup (85g) vegan chocolate chips
• 2 tablespoons (28g) melted coconut oil
• 2 tablespoons (30g) nondairy milk
• 1 cup (120g) sifted organic powdered sugar *
• vegan food coloring
• vegan edible glitter or pearl dust

How to Make Vegan Planets or Asteroids Decorations for your Galaxy Cake

prep time: 41 minutes | wait time: 20 minutes

Roll different sized balls of cookie dough and place them onto parchment paper or a silicone mat that’s on something stiff, like a tray or cutting board. I used cookie dough asteroids for the first galaxy cake I made. The second galaxy cake I made, I made cake pop asteroids by mixing the tops of the cakes I cut off with some frosting. It takes about 5 minutes to roll these balls.

Freeze the cookie dough or cake pop balls for at least 15 minutes.

Heat ½ cup (85g) vegan chocolate chips and ⅛ teaspoon coconut oil over a double boiler. Or, microwave the ingredients in 30 second increments until completely smooth and melted.

Dip each asteroid into the melted vegan chocolate chips using a fork, and set them back on the parchment paper to harden. This takes about 8 minutes.

Freeze them if your kitchen is hot, because a warm kitchen will prevent the chocolate from hardening on the counter. While they freeze, make the galaxy icing.

Mix the rest of the melted coconut oil (around 2 tablespoons / 27g) with 2 tablespoons (30g) nondairy milk.

Slowly whisk in 1 cup (120g) powdered sugar, half at a time. You’re looking for it to be a consistency that is slightly thinner than molasses.

Divide the icing into as many ramekins as colors you want to use. I used black, purple, blue, and white.

Add vegan food coloring to each bowl until desired color is achieved. I used wilton violet gel color, wilton sky blue gel color, and americolor black. If you don’t already have these colors, you can get the multi pack, which ends up being cheaper. It took me 12 minutes to make and color my icing.

Decorate the asteroids with galaxy icing and use a spoon or your finger to swirl the colors together. I spent about 2 minutes decorating each asteroid, and I made 8 altogether.

Chill the asteroids in the freezer or the fridge for a few minutes to get the icing to firm up before placing them on your cake.

How to Assemble and Decorate a Vegan Galaxy Cake

assembling time: 10 minutes | chill time: 15 minutes | decorating time: 28 minutes

Cut the tops off of any cakes that have domes at the top. They need to be level and flat before layering. This is my favorite part because everything I cut off the cakes I get to eat. Don’t worry about getting them perfectly even or you might just keep cutting and cutting until you have no more cake left. It’s like starring in your own cartoon.

Fill the cake layers with a dollop of all 3 colors of frosting. Make sure you spread it all the way to the edges of the cake. I use an offset spatula for this step, but if you don’t have one, you can use a baking spatula or a butter knife or whatever you have on hand.

Set the top layer of cake on top of the frosting layer.

Use the black frosting to complete the crumb layer of frosting.

Chill the crumb layer for 15 minutes in the freezer or 30 minutes in the fridge. You want it to harden to touch. You can make the asteroids or planets for the top of the cake while you wait.

After the frosting is hard to the touch…

Frost the cake with the final frosting layer, adding all 3 colors of frosting around the cake in any size dollops you prefer.

Smooth out the vegan galaxy frosting with an offset spatula while spinning the cake. I also used a bench scraper to smooth the sides.

Add any final decorations to the cake. I added my homemade asteroids, dappled sky sprinkles from Baking Time Club, and edible spray glitter for this cake. You can look at my list of vegan sprinkles for other decoration ideas.

Chill in the fridge or freezer until you’re ready to serve it.

Remove the cake from fridge 30 minutes before serving.

Slice into 12-16 slices. If you’re slicing it into 16 slices, you can serve it with ice cream.

Frequently Asked Questions about Galaxy Cake

Why didn’t my cakes rise?

If your cakes don’t look as tall as mine, there’s a chance they didn’t rise properly in the oven. There can be a few explanations for this. One is that you forgot to add baking soda or didn’t add enough. Baking soda also expires, so there’s a chance that your baking soda is old. The other rising agent in this recipe is vinegar. Did you remember to add vinegar?

One last thing that can prohibit a cake from rising properly is if you open the oven door while it’s baking. This is very important. You never want to open your oven door while you’re baking, especially not in the first two-thirds of the baking time. That’s why they started making ovens with windows in them, so that you can check on your cakes without opening the door.

How do I store this cake?

You know this is the best chocolate galaxy cake because it will stay good for a week, as long as it’s in a container with a lid. After the initial cutting of the cake, you have 2 options. 1. Store it at room temperature in a cake dome. 2. Cut the rest of the cake into slices and store them in a tupperware in the fridge.

Here’s a little cheat sheet for storing this cake after you make it but before you serve it.

• 1 day in advance: Store the (uncut) cake in the fridge uncovered, because the buttercream frosting acts as a barrier to protect the cake from drying out
• up to 1 week in advance: you can store the (uncut) cake in the fridge or freezer uncovered or in a cake carrier
• up to 3 months in advance: freeze the (uncut) cake until it hardens to the touch. Then wrap it completely in cling wrap to keep it from drying out or taking on any weird freezer smells. Move it from the freezer to the fridge a day before you want to serve it, but don’t remove the cling wrap until 15 minutes before you’re ready to serve it.

Can you freeze vegan chocolate cake?

If you don’t plan to eat the leftover cake within a week, wrap the individual slices in cling wrap. Place the wrapped slices in a freezer ziplock bag and store them in the freezer for up to 3 months. Or just bring it to my house. I’ll teach you how to eat a 12-serving cake in 5 days or less.

Ingredient Substitutions

• Flour: My favorite flour to bake with is all-purpose unbleached flour. If you prefer to use whole grain flours, replace the white flour in this recipe with cake flour, wheat flour, spelt flour, or whole wheat pastry flour. It will taste healthier with some of these flours though. If you want to make this a gluten-free cake recipe, replace the flour in this recipe with your favorite gluten-free flour blend. If you use raising flour or self-rising flour, omit the baking powder this recipe calls for.
• Cocoa Powder: I prefer to use fair-trade and organic cocoa powder, but you can use whatever you have on hand.
• Sugar: For the sugar in the cake portion of the recipe, you can use any number of sugars, as long as they’re vegan. Some ideas are brown sugar, sucanat, coconut sugar, raw sugar, organic sugar, or demerara. If you’re not sure if your sugar is vegan, contact the company and ask. Or just avoid conventional white sugar, caster sugar, or granulated sugar, and you should be ok.
• Baking Soda: Keep in mind that baking soda does expire, so it works best if it’s fresh/newish. If you’re out of baking soda, you can replace the 1 ½ teaspoons (10g) of baking soda in this recipe with an additional 1 ½ tablespoons (27g) of baking powder.
• Baking Powder: Keep in mind that baking powder does expire, so it works best if it’s fresh/newish. I use non-aluminum baking powder but regular baking powder is fine too. If you’re out of baking powder, you can replace the 1 ½ teaspoons (8g) of baking powder in this recipe with an additional ½ teaspoon (3g) of baking soda.
• Oil: I recommend using safflower, sunflower, avocado oil, or coconut oil for baking cakes. Those oils are for high heat, which helps you avoid transfats. However, you can use any other oil such as vegetable oil, canola oil, grapeseed oil, etc. People even make cakes with olive oil, but I don’t recommend it.
• Nondairy Milk: If you don’t have the full amount of nondairy milk that the cake part of the recipe requires, here are some options. Substitute 1:1 with water, coffee, or nondairy creamer or mix and match different nondairy milks. I often do this when I only have a little oat milk left and I use it up. Then I open a new container of almond milk or soy milk.
• Vegan Yogurt: You can use any brand of vegan yogurt you prefer in this recipe. I personally like to make my own yogurt, because my instant pot has a yogurt setting. If you’re not sure which vegan yogurts are good or bad tasting, check out my reporting of a vegan yogurt blind taste test I did.
• Vinegar: If you don’t have apple cider vinegar, you can replace it with lemon juice, lime juice, or white vinegar. You just need some sort of acid to interact with the alkalinity of the baking soda to make the cake rise.
• Vanilla: Do not substitute imitation vanilla for the real vanilla extract. Imitation vanilla is often made from something that comes out of beaver butts. I can’t make this shit up.
• Coffee: I know a lot of people (that I will never be able to relate to) avoid coffee. If you’re one of those people, you can replace the ½ cup (120ml/118g) hot coffee in this recipe with ½ cup (120ml/118g) hot water instead.
• Vegan Butter: My favorite kind of vegan butter is the Organic Whipped Earth Balance. If you avoid soy, you can use soy-free Earth Balance. If you can’t find that kind, feel free to use whatever brand you like, but I cannot promise they will make a stable buttercream frosting.
• Vegan Shortening: I use spectrum sustainable organic palm shortening because they use sustainable palm oil. If this is hard for you to find at the stores near you, there are other brands of vegan shortening, like Nutiva. However, you can also use additional vegan butter in place of the shortening. If you do this, your frosting will be less stable at room temperature, so keep it in the fridge instead of on the counter, especially if your house is warm.
• Powdered Sugar: Try to find organic powdered sugar to make sure that it’s vegan. I usually buy the organic 365 brand from Whole Foods since 1 bag is enough to frost a 2-layer cake. If it’s near the holidays, Trader Joe’s has organic powdered sugar for the same price per ounce as Whole Foods, but you’ll have to buy 2 bags because the bags are smaller.
• Asteroids: If you don’t want to make the cookie dough for your asteroids, Eat Pastry and Hampton Creek both sell vegan cookie dough. Another option is to order Coco Jolie galaxy themed vegan bon bons and top your cake with those.
• Glitter: If you have edible glitter but it’s not the spray kind, there is another way to apply it to your cake and asteroids. Dip a paint brush into the glitter and using a flicking motion to fling it onto your cake.

Galaxy Birthday Cake Video

Other Galaxy Themed Recipes

If you like galaxy themed food, check out my galaxy sushi bowl and my galaxy smoothie bowl.

For other galaxy chocolate recipes, check out my galaxy donuts and my galaxy cupcakes.

Comments or Questions?

If you make this recipe, snap a pic, post to instagram, and tag me @vegandollhouse. I love to see your creations! You can also message me through instagram or email me if you have any questions or feedback about the recipe.

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* I use mostly organic ingredients when I cook. I realize that not everyone has the disposable income to buy only organic ingredients. So, I only specify organic on the ingredients that matter: when buying the organic (or non-GMO) version is the only way to ensure that an item is vegan.

This post links to items I used when I made this recipe. If you click on the purple Buy Now button on a product page, you will go to a website (like Amazon) where you can buy the same product I used. Sometimes, the store you purchase from (Amazon, Etsy, etc.) will pay me for referring you. This costs you nothing extra, and I would never recommend a product that I don’t use. These affiliate programs help me buy the ingredients to create these recipes for you. Read more about this in my privacy policy.

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I reshot these pics in 2023, so below are the old pictures from 2018.