Hello gorgeous! Slice into this stunning white rainbow bundt cake to find something special inside… a bright rainbow! My Rainbow Bundt cake is as bright and cheery on the inside as it is on the outside. And the biggest win of all is that it’s SUPER simple to make with my easy tips, tricks, video, and recipe below. Let’s dive right in, shall we?

RainboWS 100 WAYS

I love making rainbow themed cakes! For the past (over ten) years, I’ve always looked forward to just about every holiday (big or small) because that means that I get to make themed cakes to match the occasion! Each holiday is a fun excuse to bake something special.

St. Patrick’s Day is no different! You’ve seen me hide rainbows in my stacked cake layers. You’ve seen me hide rainbows in my buttercream. And you’ve seen me decorate the outside of each and every one with some kind of rainbow flair.

all the rainbow things

With rainbow stripes, rainbow ruffles, rainbow rosettes, rainbow Russian piping tip flowers, rainbow petals, rainbow swirls, rainbow nonpareils sand art, and even cakes rolled entirely in rainbow sprinkles… needless to say: we have a theme going on. If you’ve been following me for even a little while, you know I love to find new ways to add bright colors inside and outside of my cakes.

It’s time to make it into a bundt

Adding a rainbow inside a bundt cake was inevitable, and with St Patricks Day around the corner, I knew it was time to finally try to add a rainbow inside a bundt cake.

Inspiration, or?

When I come up with fun ideas in the kitchen for my cakes, after you’ve been doing this as long as I have, I tend to know what is possible in cake land. Different designs hit my mind without stopping (which is why I keep a notebook in my purse at all times to write down design and flavor that come into my head so that I don’t forget them!). Contrary to what some may believe, this was one of those ideas. I’ve made bundt cakes before with different designs inside. I’ve made cakes with surprises inside the slices. So imagining a rainbow inside a circle bundt pan sounded like a natural way to let the rainbow arch shine inside (much like the popular zebra or marble design and method we’ve all seen inside cakes). I couldn’t wait to try this out and see if it would actually work with rainbow colors and my white cake recipe. Figuring out how to execute it wasn’t hard because I’m used to thinking backwards and upside down for some of the suprise-inside cakes I’ve made.

Credit

I had received a few bundt pans for Christmas, so I had already had this cake in mind and saved it for the occasion. After executing my vision independently, photographing it, videoing the tutorial you see here below, and sharing it on my Instagram page without ANY knowledge beforehand of anyone else doing it – something crazy happened. It was quickly brought to my attention that I was not the first to try this technique of putting a rainbow inside a bundt pan. When you’ve been making cakes as long as I have, this is never really a huge surprise because everything has been done before in one way or another.

Where have we seen it?

In fact, bakers more than 10+ years ago have already done this beautifully, including but not limited to, Taste of Home (2018), Not Martha (2011), Betsy Life (2014), Betty Crocker (2011), and the list goes on and on and on. I even have a highlight on my Instagram called “rainbow bundt” with a few more who have done this before (many of them pre-date the past three years).

invitation to you:

I don’t feel comfortable listing them as my “idea credit.” It feels strange. Why? Well, because I technically didn’t see any others before creating my own, I had seen bundt cakes filled entirely with rainbow (instead of a small outline of one like we have here today) which have already flooded the internet.

I do, however, encourage you to check out the many other versions, recipes, and tutorials of this cake if you so desire, and pick the one that makes the most sense to you and your baking journey.

That said, and all drama aside (cakeland is supposed to be fun, am I right?), I’m happy to add my rainbow bundt cake here to the lineup. I hope it can continue, as they all have, to inspire bakers all across the world to hop into their kitchens and try something new to them! This time with my version of the rainbow bundt cake. 🙂

HOW TO MAKE THE RAINBOW BUNDT CAKE DESIGN:

This cake is all about adding the batter in layer by layer into the bundt pan. I’ve outlined the steps pretty specifically below in the directions. If you’re more of a visual learner, I’ve also included a video for you to see the entire process.

The main trick is to remember to pipe the colors carefully in the center ring of the last color without touching the sides. I know the video is fast, but it shows this perfectly. Tap the pan down to make it flat, then pipe the next color again. Also, don’t make the dang rainbow upside down like I did, haha. You can, I mean, it still looks like a rainbow, but if you want the red to be on the top/outside then make sure to pipe it first. 🙂

What you’ll need:

There’s a few different tools you’ll need to make your rainbow bundt cake as easy as possible.

CIRCLE BUNDT PAN:

First up: You’ll need a circle bundt pan!

Image source: Amazon

This pan is shaped like a giant donut, and that shape is super important for the design. If you use a different variety of bundt pan, the classic rainbow half circle may not show through as clean. I have the one linked HERE.

PIPING BAGS:

Next, you’ll need 7 piping bags. I used the 12″ ones HERE. Don’t snip of the end of the piping bag until you’ve filled them with the colored cake batter.

GEL COLORS:

I love using the Americolor gels HERE for colorful projects like this one. They’re super vibrant and tint whatever you’re using super well.

BOWLS and SPOONS:

Having different bowls will really help keep the measurements pretty even, and will also make it easier to mix up the colors separately in their own bowl. I use the kid’s bowls from Target, but you can use cereal bowls. Hey, if you don’t want to do any dishes, you can even do paper ones and then toss em afterwards.

As for the drip on the rainbow bundt cake, I just used my white chocolate drip recipe below, and added on all the fun rainbow sprinkles/jimmies on top! Make sure to grab the “Bright white” chocolate candy melts so you’re drip isn’t translucent or ivory. The white really makes those colors pop!

Let’s take a peek the process below:

That’s it! I can’t wait to see all your rainbow bundt cakes this St. Patrick’s Day season and always!

Happy Baking, friends!

xo,

Mandy

Get the Recipe: Rainbow Bundt Cake

A bright and festive rainbow hidden right inside a vanilla bundt cake!
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Ingredients
 

White / Rainbow Bundt Cake

  • 3/4 cup buttermilk , room temperature
  • 2/3 cup sour cream , room temperature
  • 4 egg whites , room temperature
  • 1/3 cup vegetable oil
  • 1 Tablespoon vanilla
  • 1 15.25oz Box Cake White Mix, I used Duncan Hines for the best taste and texture, but any other brand will be similar.
  • rainbow gel colors (red, orange, yellow, green, blue, purple)

White Chocolate Ganache Drip

  • 1 cup "bright white" chocolate candy melts , I used Wilton brand, but I also love Sweet Tooth Fairy chocolate melts
  • 1/4 cup heavy cream

Extras

  • 1/2 cup rainbow jimmies/sprinkles

Equipment

  • 1 Circle Bundt Pan
  • piping bags
  • bowls & spoons

Instructions
 

For the rainbow bundt cake:

  • Preheat the oven to 325 degrees, and prep your round bundt pan with a swipe of shortening and dust of flour. Set aside.
  • In a large bowl, whisk together all the ingredients for the cake except for the cake mix and food gel colors. Sift in the cake mix and gently stir until it's barely combined.
  • In the 6 separate small bowls, scoop in a generous 1/2 cup of white batter in each bowl. Add one drop(ish) of gel coloring in each bowl, and gently stir to disperse the color throughout. Fill 6 piping bags carefully with the colored cake batter (I love to use a drinking glass to fold the piping bags over for filling the piping bags).
  • In the bottom of the circle bundt cake, spread in a small layer of the white cake batter (see video for a better visual). Snip off the tip to create a small circle opening (about the size a small marble could get through.
  • Next, pipe the first color in a ring, avoiding the outside of the first white layer. (I did purple, which technically makes the rainbow upside down – oops! But you can pipe red first for a more traditional look). Tap the pan to make the batter flat before adding the next color.
  • Next, pipe the second color in a ring around the center of that color stripe (see video). Repeat with the remaining colors – remember to tap the pan to keep it flat before adding in the next color.
  • Next, add about 1/2 cup of white cake batter into another piping bag. Pipe a white layer in the middle again (just like the previous layers), and tap the pan to flatten.
  • Finally, pipe the rest of the white cake batter around the top in an even layer. Bake for 25-27 minutes until the center of the cake is baked through. Remove the bundt cake from the oven, let cool in the pan for about 30 seconds, then flip the bundt cake onto a wire rack to cool completely.

For the White Chocolate Ganache Drip

  • In a glass microwave-safe bowl, stir together the white chocolate candy melts and heavy cream. Heat for 1 minute, then stir until smooth. You may need to add another 15 seconds and stir again if needed. Add to a drip bottle, let cool slightly, then add the drip to the cake. Immediately add on the sprinkles.
  • Slice to reveal your hidden rainbow, and enjoy!

Video

Originally published summer 2022, republished 2/15/2023