Cake Details: Rustic Rainbow Striped Cake

Cake Details: Rustic Rainbow Striped Cake

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This Rustic Striped Rainbow Cake is made with colorful layers of classic vanilla cake from a cake mix, sandwiched with vanilla buttercream, all brought together with lots of colorful stripes and splashes of rose gold!

I made this cake a few weeks ago, as part of a cake collaboration over on Instagram. We were at the beginning of quarantine and in some serious need of color!

Rainbow striped cake slice with coffee

All about this Rainbow Striped Cake

The Cake

The cake is a classic vanilla cake. I actually used a boxed cake mix, with a few adjustments to the back of the box recipe, aka a doctored up cake mix.

I used half the batter for 3 layers for this cake, and the other half of the batter for 12 cupcakes. If you’re looking for a vanilla cake from scratch recipe, you can use this vanilla cake recipe from my sprinkle fault line cake!

To keep with the rainbow theme, I also colored my three layers three different colors: purple, green, and pink.

I used Americolor Gel colors, but feel free to use your favorite food coloring can also be used for this project!

The Filling & Frosting

The filling for this rainbow striped cake is a classic vanilla swiss meringue buttercream. I love my swiss meringue buttercream recipe as it is so rich and indulgent all on its own! It’s also the perfect base for adding any flavors! (Let me know if you want to see the recipe for that!)

You can of course easily use any other type of buttercream as well to get the same look! I loved the contrast of white against the colors of the cake!

Rainbow striped cake with sprinkles & offset spatula

Decorating the Rustic Rainbow Striped Cake

I call it rustic, because it is unlike other striped cakes where you get clean lines. I could have gone further with the stripes, but what I really liked this unfinished rustic look.

Step #1: Stack & Fill the cake

Once the cake layers are baked and cooled completely, then you’re ready to stack and fill the cake. I like to bake my cake layers a day in advance and then stick them in the fridge so that they’ve cooled completely and are easy to work with.

This cake had three cake layers with vanilla buttercream between each layer.

Step #2: Crumb Coat and Chill

After the caked is stacked and leveled, apply a thin crumb coat, and let it chill in the fridge for at least 30 minutes, until the buttercream is firm to touch.

I use Swiss meringue buttercream so it never forms a crust, but if you use American buttercream, it would develop a sort of crust.

Rainbow striped cake with cake tools.

Step #3: Creating the striped look

Once the cake has chilled, it’s time to decorate.

Apply a generous layer of buttercream.

Then with an offset spatula or bench scraper, smooth out the buttercream until it is an even layer. Continue going around the cake, until it’s even, but make sure that it’s still a pretty thick layer.

Then, finish and straighten the top. Then chill the cake again for at least 30 minutes! The buttercream should be cold and firm at the end.

Step #4: Color your Buttercream

While the cake is chilling, you can color your buttercream. For this cake, I used 6 different colors.

Use about a half cup of buttercream for each color, and fill them in piping bags.

Multicolored frosting in piping bags with plain cake

Step #5: Create the stripes

You’ll definitely need a striped comb for this project.

Once the cake is cold and chilled, place the cake on a cake turntable, and drag your striped comb, go around the cake. Try to get as tight as you can with the cake. The cleaner the ridges, the easier they will be to fill.

After this step, as extra insurance, chill the cake again. This time, I chilled it for 45 minutes.

Step #6: Fill the stripes

Once you’re ready to fill your stripes, fill 6 piping bags with the different colors, and cut a bit of the top to create a small hole.

Pipe the colors into the ridges, as you would like. Then, using a bench scraper, wipe off the excess buttercream. Make sure to wipe your scraper after each swipe. Keep going until the stripes are revealed, and you are happy with the look!

Step #7: Finish with Rustic Rainbow Striped Cake

To finish the cake, dip a food safe brush into some edible rose gold edible paint and splatter it on the cake. Finish with some gold sprinkles, if desired.

And Voila! All done with the Rustic Rainbow Striped Cake!

Rainbow striped cake inside with cake slice on white plate

A Few Tips:

  • Cake: one cake box made enough cake batter for three 6-inch layers (used for this cake) and 12 additional cupcakes. If you want an 8-inch cake with three layers, you would use all the batter!
  • Buttercream: I use a Swiss Meringue Buttercream, but you can easily substitute with American Buttercream or Italian Buttercream if you prefer!
  • Stacking the cake: Keep the flattest cake layer for the top of the cake. This way there the top of the cake looks sharp.
  • Decorating the cake: Make sure to chill the cake in the fridge at each step as recorded. That is the only way that you can control the look of the stripes!
Rainbow striped cake top view

If you do make these, tag me on Instagram at Sprinkles By Anum, or by using the hashtag #sprinklesbyanum

Cheers,

Ready to make some this Rainbow Stripe Cake?

Shop the look:

Rainbow striped cake

Prep Time2 hrs
Cook Time45 mins
Resting time2 hrs
Total Time4 hrs 45 mins
Course: Dessert
Cuisine: American
Keyword: Cake

Equipment

  • 3 Piping bags
  • Wilton 2D Tip
  • Bench Scraper
  • Striped comb

Ingredients

Vanilla Cake

  • 1 box cake mix
  • 1/4 cup butter
  • 1/4 cup vegetable oil
  • 4 large eggs
  • 1 cup milk
  • gel food coloring

Swiss Meringue Buttercream

  • 180 grams about 6 large egg whites
  • 360 grams granulated sugar
  • 450 grams unsalted butter room temperature cubed
  • 1 tsp vanilla

Assembly

  • Gold Sprinkles
  • Gel Food Coloring

Instructions

Vanilla Cake

  • Preheat oven to 350F and grease and flour three 6” cake rounds.
  • In a large bowl, add the cake mix and all the other ingredients, except for the food coloring. Mix well together.
  • Divide the batter in half – you only need 1/2 of the batter for the 3 cake layers.
  • Then divide the cake batter into 3 equal portions, and color each of them.
  • Pour each into prepared cake tins.
  • Bake for 20-25 minutes, until a toothpick inserted into the center comes out mostly clean.
  • Cool until ready to use.

Vanilla Swiss Meringue Buttercream

  • Place egg whites and sugar into the bowl of a stand mixer, whisk until combined. 
Place the bowl over a hot water bath on the stove and whisk constantly until the mixture is hot and no longer grainy to the touch or until it reaches a temperature of 165 degrees F on a candy thermometer. 
Place the bowl on your stand mixer and whisk on medium-high until the meringue is stiff and cooled (the bowl is no longer warm to the touch (approx. 5-10mins).
 Switch to a paddle attachment. Slowly add cubed butter and mix until smooth. Add vanilla and continue to whip until smooth.

Cake Assembly

  • Spread some buttercream on the cake board.
  • Place one layer of cake on a cake board and place it in the fridge for 5-10 minutes. This will help the cake stick to the cake board and not slip as you stack and frost.
  • Remove from the fridge.
  • Top with approximately 1/3 cup of frosting and spread evenly.
  • Repeat with remaining layers and apply a thin coat of frosting all over the cake for the crumb coat. Chill for 20mins.
 Frost with a generous layer of frosting and smooth the sides.
  • Place cake in the fridge for 30 minutes.
  • Once chilled, drag the striped comb to create ridges for the stripes.
  • Place cake in the fridge for another 45 minutes to 1 hour until buttercream is completely firm.
  • While the cake is in the fridge, color the buttercream for the stripes. Color 1/2 cup of frosting for each of the 4 colors – yellow, green, purple, and red. Place each color into separate piping bags.
  • Once the cake has chilled, remove from fridge and place on the cake turntable.
  • Pipe the ridges with the colored buttercream, ensuring ridges are filled.
  • Once all the ridges are filled, using a bench scraper smooth the buttercream, wiping the bench scraper after each swipe. Keep going until stripes are revealed.
  • Use the leftover buttercream and a 2D piping tip to create the top.
  • Once you're happy with the look, finish decorating the cake with a splatter of rose gold paint & gold sprinkles if desired.
  • Slice and serve at room temperature.

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