The happiest bundt you ever did see, this Rainbow Bundt Cake beefs up boxed cake mix to make a colorful and moist cake with a vanilla glaze kids and adults will love.
It's almost St. Patrick's Day -- and what's better than rainbow everything? The kids are still on a rainbow kick, and the birthday boy has requested this for his 7th birthday coming up.

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Why You Need To Make This Rainbow Bundt Cake
Doesn't this cake just scream childhood dreams? Rainbow cakes have been a favorite in our house for a couple of years strong -- with each child declaring it their favorite.
I wanted to mix it up a little bit by putting the cake in bundt form -- which really cuts down on the time required. There's no need to bake the cakes in two batches, line your cake pans with parchment paper, then let the layers cool before having to frost the whole thing.
This rainbow bundt cake is the Easy Rainbow Cake's worn out mom, just wanting to wear her yoga pants and sweatshirt and sip on wine in peace for 5 minutes. In a closet. That's this cake. Zero fuss required.
How to Make a Rainbow Bundt Cake
Follow these easy steps to have a bundt cake ready to go in no more than 45 minutes -- and that includes the baking time!
Step 1: Jazz up boxed cake mix.
Preheat your oven and grease and flour your bundt pan.
Using a box of white or yellow cake mix (Betty Crocker, Duncan Hines...whatever you prefer), add in instant pudding (in powder form), eggs, oil, water, and sour cream.
Step 2: Divide batter into 6 bowls.
Evenly distribute the batter into each of the 6 bowls. You'll have a heaping ½ cup of batter in each bowl.
Step 3: Dye the batter & pour in bundt pan.
Using gel food coloring (or whatever kind you prefer), dye each bowl its designated color of red, orange, yellow, green, blue, and purple.
Starting with the red batter, pour the batter evenly at the bottom of the greased and floured bundt pan. Then layer the orange batter on top of the red. Do not mix the colors. If there's a small gap you can use a spoon to gently spread the top-most batter but be careful not to combine the colors. Keep layering each color on top of the next until all of your colors are poured.
Step 4: Top with a Simple Vanilla Glaze
No need for frosting here. This 3-ingredient vanilla glaze requires confectioner's sugar, vanilla extract, and milk to be stirred with a spoon until combined. One the cake is cool, spread the glaze on the top and you're ready to eat!
Other Happy Desserts
- Meyer Lemon Curd Tart with Shortbread Crust
- Lemon Bundt Cake with Lemon Glaze
- Cranberry and Rosemary Curd Tart
- Nothing Bundt Cake Copycat
- Vanilla Merengue Cookies
xox,
kathryn
As always, if you make anything from the blog, be sure to let me know! I love hearing from you in the comments on this post below or find Worn Slap Out on Facebook, Instagram, or Pinterest!
Rainbow Bundt Cake (Using Boxed Cake Mix!)
Ingredients
For the cake:
- 1 package white or yellow cake mix
- 3.9 ounce box instant vanilla pudding
- ¾ cup sour cream
- 4 large eggs
- ½ cup water
- ½ cup vegetable or canola oil
- food coloring
For the glaze:
- 1 cup confectioner's sugar
- ½ teaspoons pure vanilla extract
- 2-3 Tablespoons milk
Instructions
- Preheat the oven to 350˚F. Grease and flour the bundt pan. Set aside.
- In a large bowl, mix the cake mix, instant pudding powder, sour cream, eggs, water, and oil until combined. Separate the batter evenly in 6 different bowls (each bowl will have about ½ cup of batter). Place red food coloring in the first bowl of batter, orange in the second, then yellow, green, blue, and purple.
- In your greased and floured bundt pan, gently pour the red batter evenly at the bottom of the bundt pan. Unless you have to because there's a large gap, don't spread the batter. Then pour the orange batter right on top of the red, being careful to not mix the two colors together. If there's a gap, use a spoon to very gently touch only the top color. Repeat until you have all of your layers.
- Bake cake for approximately 35 minutes or until toothpick inserted into the center of the cake comes out clean. Let cool for 10 minutes before inverting and removing the cake from the bundt pan onto a wire rack to cool completely.
- Make the glaze: Combine all of the glaze ingredients into one bowl until well mixed. If you want the glaze to be thicker, add more sugar (or add more milk if you want it thinner). Set aside for 5 minutes to slightly thicken. Spread over the top of the cooled bundt pan.
Shana S.
This looks so fun and delicious! We will definitely save this recipe for a birthday or two!
Kathryn
Aww thanks so much, Shana! ❤️❤️❤️
Jolene
My 10 year old granddaughter and I made this for her birthday cake. She did everything except spreading the layers, which I helped with. It was beautiful and really good. Very nice texture and flavor.
Kathryn
I'm so glad you enjoyed it and made memories doing so!
Shiska
What size is your cake mix? Was this done with an 18.25 oz box?
Kathryn
15.25 oz boxes!