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Rainbow Ganache Cake

Rainbow Ganache Cake is a fun and festive, but super simple, cake recipe. White chocolate ganache is delicious and so easy to dye with vibrant colors! This rainbow cake is the best dessert to celebrate a birthday with or bring to any party!

My Favorite Rainbow Cake Recipe

Welcome to post 2 in Valentine’s week here and at Confessions of a Cookbook Queen!

I guess this cake isn’t really Valentinesey…

But it totally could be…I mean, just use red and pink ganache…

The idea for this cake came from all those cute Melted Crayon Art projects all over Pinterest.  Have you seen those?  SO fun!

And even though rainbows aren’t your typical Valentine’s symbol I’m thinking that no one would be UPSET if a rainbow happened on Valentine’s Day.

Rainbows are basically love in the sky, so I think this totally makes sense.

Rainbow Ganache Cake | Cookies and Cups

A Homemade Rainbow Ganache Cake

This cake is pretty darn easy…I mean as far as cakes go.

I am by no means an expert cake decorator…as a matter of fact I have grown to moderately despise cake decorating.

After one too many disasters, I decided my patience level in not suited for cake artistry.  I am more of a slap it together kind of girl.

So this cake is perfect for me…simple frosting, drippy ganache, and swirled colors.  Basically you can’t mess it up…

Just bake your cake.

I made chocolate…but I am sure there are you girls out there who would take this whole cake to the next level with a swirled cake inside, or a rainbow layer cake.  Go for it.

I “crumb coated” the cake…which is a thin layer of frosting that you smooth on first and let set.  It just prevents you from getting cake crumbs in your final product.  It seals in all the crumbs.

Then I went over the crumb coated layer with a a smooth layer.

I used my recipe for buttercream.

A collage of two photos of a frosted layer cake

How to Make White Chocolate Ganache:

After you’ve frosted the cake, go ahead and make your white chocolate ganache.

Just chop up some white chocolate fairly finely…

Finely chopped white chocolate on a cutting board

Now place your chopped white chocolate in a bowl and pour some nearly boiling heavy cream on top.

Stir the cream and white chocolate together until it melts.  If you need to, you can microwave it slightly so all the white chocolate melts.

Glaze ingredients in a mixing bowl with a spoon

Next add some light corn syrup to the ganache.  This helps give it a little shine.

Then separate your ganache into bowls in equal proportions…the amount depends on how many colors you are using.

Melted white chocolate mixture in several custard cups

I used Candy Coloring to tint the ganache…with the white chocolate in there, I was worried that regular food coloring wouldn’t work.

Two boxes of candy colors food coloring

I just added a little bit until I got the colors that I wanted.

Custard cups with a variety of colors of white chocolate icing

Then start with one color at a time.  Place a nice spoonful in the center of the cake and using an off-set spatula, or large spoon push the ganache to the edge, letting it drip down the sides itself.

Purple ganache dripping down the side of a white-frosted layer cake

Continue around the cake cake alternating colors…

Rainbow Ganache Cake | Cookies and Cups
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White Chocolate Ganache

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  • Author: Cookies & Cups
  • Prep Time: 20 min
  • Total Time: 30 min
  • Yield: 1 batch 1x
  • Category: Dessert
  • Cuisine: American


Rainbow Ganache Cake is a fun and festive, but super simple, cake recipe. White chocolate ganache is delicious and so easy to dye with vibrant colors! This rainbow cake is the best dessert to celebrate a birthday with or bring to any party!


  • 4 oz white chocolate, chopped finely
  • 1/4 cup heavy cream
  • 3 Tbsp light corn syrup
  • candy coloring


  1. Chop your white chocolate and place it in a medium sized bowl.
  2. Heat heavy cream in microwave about 1 minute until it’s very hot.
  3. Pour the heavy cream over the white chocolate and let it sit until the chocolate melts, stirring often.
  4. If the white chocolate doesn’t fully melt microwave for an additional 20 seconds until melted.
  5. Add in corn syrup and stir until incorporated.
  6. Place mixture in the refrigerator for approximately 10 minutes until cooled.
  7. When chilled, separate into bowls and add color to each.
  8. Pour over top of the cake, pushing to edge allowing ganache to drip down over the side of the cake.


  • Serving Size: 1 piece of cake
  • Calories: 100
  • Sugar: 11.9 g
  • Sodium: 15.9 mg
  • Fat: 5.8 g
  • Carbohydrates: 11.9 g
  • Protein: 0.8 g
  • Cholesterol: 9.1 mg

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51 comments on “Rainbow Ganache Cake”

  1. I want to make this for my daughters birthday, but is there anything I can use for the ganache other than chocolate. My husband won’t eat it.

  2. That looks amazing! -I was wondering if it would be possible to substitute the corn cyrup for something else, as I can’t find it where I live…?

  3. I’m totally envisioning this as a St Patrick’s Day dessert and sprinkling gold coins all around the bottom of the rainbow ganache drippings!

    Soooo Cute!

  4. Made this delicious cake yesterday and followed all your instructions for the ganache. It was a big hit. I used regular food coloring and the colors worked out great. Thanks.

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