Mermaid Buttercream Cake

This mermaid buttercream cake is made with tender vanilla cake layers and creamy vanilla buttercream that looks like mermaid scales. The cake batter is colored with purple, blue and green gel food color that are swirled together for a beautiful mermaid cake. 

This cake isn’t complete without the handmade fondant mermaid tail coming out of the top of the cake. 

The tri-colored buttercream scales use a simple technique called Pulled Dots that looks stunning when it’s completed. I alternated the buttercream colors for a cool pattern with a subtle shimmer effect with gold highlighter luster dust. The gold shimmer makes this fondant mermaid tail shine.

In this tutorial, I also give you a printable fondant mermaid tail stencil for you to download for your mermaid tail. 

It’s a perfect cake for birthday or summer parties. This mermaid cake is sure to impress and make everyone happy! 

Tips for success: 

• Read through all the ingredients and instructions so you can get a better idea of how much time and what you need to make this cake.
• For the mermaid tail: depending on the thickness of the fondant mermaid tail, this can take an average of 4-12 hours to thoroughly dry. You can mix in tylose powder to stiffen and dry the fondant faster. I do recommend making the tail the day before you decorate the cake. 
• In this cake recipe, you need 1 cup buttermilk, if you don’t have any buttermilk on hand you can easily use 1 cup whole milk mixed with 1 TBSP lemon juice or white vinegar to make your own. 
• You can bake the cake layers ahead of time. Simply wrap the cake layers in plastic wrap and freeze up to one month. 
• You can make the buttercream a day ahead and refrigerate it overnight. Then take them out to come back to room temperature. Make sure the buttercream is at room temperature before re-whipping.
• A single batch of this cake recipe makes three, 6-inch round cake layers or two 8-inch round cake layers. Double the cake recipe to make enough cake batter for three, 8-inch cake layers.
• Be careful not to overmix this cake batter or else the cake will come out dense. Mix until all ingredients are well incorporated. 
• Food coloring gets darker over time, so it’s best to gradually add the food coloring, which is best for pastel colors.  
• Serve cake at room temperature. 

What Tools You’ll Need to Make This Cake: 

• 3, 6-inch cake pans or 2, 8-inch cake pans
• Offset spatula 
• 8-inch or 10-inch white cake board 
• Serrated knife or cake leveler 
• Turntable 
• Bench scraper or cake scraper
• Piping bag (I use silicone reusable bags)
• Round piping tip 
• Whisk or sifter
• Rubber Spatula
• Non-Stick Cooking Spray and Parchment Paper
• Ice Cream Scooper with Trigger Release (for dividing cake batter evenly)
• Cake Stand, optional
• Leaf green gel food coloring 
• Neon green gel food coloring
• Purple gel food coloring
• Sky blue gel food coloring
• Small fondant rolling pin 
• Silicone fondant mat
• 8-12 ounces Light purple fondant 
• Tylose powder, optional
• Fondant molding tools
• X-Acto knife
• Long wooden skewers
• Fondant Mermaid Tail Stencil
• Cornstarch and Vegetable Shortening
• Edible gold highlighter luster dust
• Clear alcohol (Vodka) or Lemon extract

My hope for you is to be to feel more confident with baker and cake decorator by the end of this tutorial. Here’s how to make this Mermaid Buttercream Cake! 

Let’s Make Some Cake! 

How to Make a Fondant Mermaid Tail 

I suggest making the fondant mermaid tail before baking the cake or make the tail the day before you decorate the cake. This way it can dry thoroughly while you are getting everything else done. 

Notes before starting, depending on the thickness and humidity of the fondant mermaid tail, this can take an average of 4-12 hours to thoroughly dry. You can mix in tylose powder to stiffen and dry the fondant faster. If the fondant mermaid tail isn’t dry enough then gravity will take over and break it off the support skewer. 

1. On the silicone fondant mat, roll out the light purple fondant to a thickness of 3/16 inch – 1/4 inch. If the fondant is a little sticky, then use a small amount of cornstarch. 
2. Next, use a Fondant Mermaid Tail Stencil to cut out the shape of the tail. Use a sharp knife like an X-Acto knife to get clean edges. Click the link here to download and print the Fondant Mermaid Tail Stencil. 
3. Insert a long wooden skewer running through the center of the tail to help the tail stand up easier inside the cake. 
4. Then smooth the cut edges with a small amount of shortening and use a pointed fondant molding tool to create the signature tail fin lines. 
5. Set the fondant tail aside on a piece of parchment paper to dry thoroughly depending on how thick the piece of fondant is. If your fondant is mixed with tylose powder, then this process can take at least 2 hours, or it’ll take up to 4 hours to dry normally.  

Mermaid Marble Vanilla Cake 

1. Preheat oven to 350 °F. Spray three 6-inch round cake pans or two 8-inch round cake pans with non-stick spray, line the bottom of each pan with parchment paper and spray again. Set aside.
2. In a medium-size bowl, whisk and stir together the all-purpose flour, cornstarch, baking powder, and salt. Set aside. 
3. In the stand mixer bowl fitted with a paddle attachment, beat the butter, oil, and sugar on medium-high for 5 minutes.
4. Add the eggs, one at a time to the stand mixer bowl and beat on medium until well incorporated.
5. Turn the mixer on low and add the flour mixture to the butter mixture until fully incorporated. 
6. Pour in the buttermilk and add vanilla extract. 
7. Divide the cake batter into three equal parts. Then color each bowl of cake batter. In one bowl, add purple gel food color, in the second bowl add sky blue gel food color and in the final bowl add neon green and leaf green gel food color. Mix the cake batter and food color with a rubber spatula and scrape down the sides of the bowl. 
8. Evenly divide the colored cake batter into the three 6-inch cake pans. Use a wooden skewer to swirl the three colored cake batter together into each pan.  
9. Bake for about 35-40 minutes or until a toothpick inserted into the center of each cake comes out clean or with just a few moist crumbs. 
10. Remove cakes from oven and let cool in pans for 10 minutes before inverting onto cooling racks to cool completely — wrap cakes in plastic wrap and place in the freezer to chill for 30 minutes. 

Mermaid Vanilla Buttercream 

1. In the stand mixer bowl fitted with the paddle attachment, beat the butter until light and fluffy, about 5 minutes.
2. Turn the mixer to low and gradually add the powdered sugar, followed by the heavy cream, salt and vanilla extract. Mix until incorporated completely. Scrape down sides of the bowl. 
3. Turn the mixer to medium-high and beat the buttercream for about 5 minutes until light and fluffy. 
4. Turn the mixer on low and mix for 2 minutes to push out any air bubbles. 
5. Divide the buttercream into three bowls and color one bowl of buttercream light purple, one bowl of buttercream a light green and one bowl of buttercream a light blue.
6. Then prepare three piping bags with round piping tips and filled 2/3 of the way with buttercream. 

How to Put It All Together 

1. Remove the cake layers from the freezer and unwrap the cake layers. Next, use a serrated knife to cut off the dome of the cakes to make the layers flat and even. 
2. Add a small amount of buttercream onto the center of the cake board. Layer the chilled mermaid marbled cake, cut side up onto the cake board. 
3. Then pipe a ring of blue buttercream to the outside edge of the cake, followed by the purple buttercream and in the center pipe the green buttercream. Use an offset spatula to smooth the layer of buttercream. 
4. Place another cake layer cut side down over the top. Repeat the process for another layer — Crumb coat and freeze for 20 minutes.
5. Starting from the bottom of the cake, pipe a single dot about 1-inch of the buttercream. Use an offset spatula to press and pull the dot towards the side of the cake. Then pipe another dot above the previous dot. Repeat the process until you have one column completed.  
6. To start a new column, pipe the next dot overlapping the previous pulled dot. Alternate the colors to create a scale effect. Repeat the process all over the whole cake. Place the cake into the fridge to set the buttercream. 
7. Then mix 1/2 tsp of gold highlighter luster dust and one drop of clear alcohol (lemon extract) until it looks like paint. Add more luster dust or clear alcohol to adjust the paint consistency. 
8. Then with a small brush, paint the edge of random buttercream scales to give a shimmer effect. 
9. Paint the gold luster dust on the edges of the mermaid tail for the finishing touches. Then carefully insert the tail into the center of the cake, standing up straight to complete the cake. 

You May Also Enjoy: 

• Watermelon Cake (tutorial)
• How to Cut & Serve Cake (free guide)
• Common Baking Mistakes & How to Avoid Them (free ebook)
• How to Decorate Your First Cake (free course)
• Cake Decorating Tool Kit (24-piece kit with free shipping) 

In this tutorial, we are working with simple buttercream techniques and a more intermediate technique with the fondant mermaid tail. This mermaid buttercream cake takes several basic techniques that’ll elevate your skills and give you the confidence to take on any cake challenge! 

My goal is to help you become a better and more confident baker, let me know in the comments below what’s your #1 baking and cake decorating problem? 

Happy Decorating! 

Hey, if you liked this tutorial, you really should check out, Cake Decorating Creator Program, my online cake program. I coach you on everything I teach on these cake tutorials so that you can uplevel your baking and decorating skills. We 10x it so you get the results you want most. Like any new skill, it’s important to learn from the ground up to build a foundation, so you can take on any cake challenge. It is an investment your future self will thank you for. Check it out at XOKatieRosario.com/creator-program. I will see you there!

 

Watch The How-to Video Below: 

Click the link here to download and print the Fondant Mermaid Tail Stencil!

 

Pin it! Save it for later! 

 

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