Rainbow Surprise Cake

This cake is so much fun! I was in a serious time crunch this year for the girls’ 7 & 9 year birthday party, so I needed something using basic ingredients with minimal decoration and no fondant! Thankfully I stumbled across this Rainbow Cake from fellow Michigan blogger, Whisk Kid, at the Nth hour.

The party theme this year was a Construction Site Carnival. We’re under construction with a dumpster in the front yard and a front-end loader in the back…so I just decided to work with it. Scaffolding worked well for the concession stand, construction debris made adventure golf more fun, gravel piles and lumber came in handy as well.

The important thing about making this cake, is making it after hours or when the kids are out of the house so they can’t see the process. Cutting it has to be a surprise. My girls were VERY concerned about the cake. They saw the plain white cake and kept asking me “are you SURE you’re done decorating?” Katie was concerned enough that she went into the garden and picked raspberries to put on top. The gasps and glee when the cake was opened…priceless.

Awesome Rainbow Cake
I’ve made this a few times now, with bright colors and with pastels. It would be great with green and red batter for Christmas, or blue and red batter for 4th of July!

2 3/4 cups flour
1 1/2 teaspoons baking powder
1 teaspoon baking soda
1/2 teaspoon salt

2 cups dairy-free milk (I like So Delicious Coconut) + 2 teaspoons vinegar, set aside to thicken
1 1/2 cups white sugar
2/3 cup oil
1 Tablespoon vanilla

Gel Food Coloring (I use AmeriColor soft gel paste)
1.) Preheat oven to 350.
2.) I only have two 8-inch round cake pans, these cook quickly, so it works fine. Trace your pans onto some parchment paper and cut out 6 rounds.
3.) Whisk the flour, powder, soda and salt together in a big bowl.
3.) Mix the thickened dairy-free milk, sugar, oil and vanilla together.
4.) Add about 1/2 the liquid into the dry ingredients, and beat it pretty well. Yes, I know beating causes gluten formation and a potentially tough cake, but this is a case where you can’t have lumps or you cake is speckled with white. Add the second half of the liquid and fold in gently. I really screwed this up the first time, had tons of lumps and had to run the batter through a sieve/food mill. Hopefully you have better luck, but the sieve option is there as a back up.
5.) Using a scale, divide the batter up into 6 equal portions. I did this by zeroing out a big empty bowl, adding the batter to determine total batter weight. Then divide total batter weight by 6 and measure out 6 portions to color.
6.) Color them up! Gel color works much better here than regular drops, which don’t have nearly the color options or vibrancy.
7.) Line each 8-inch pan with parchment and spray with cooking spray.
8.) Bake for 10-12 minutes, until the center is set.
9.) Carefully remove cake from pan to a cooling rack, add a new parchment liner to the pan, re-spray and cook the next layer color.
10.) Frost & build the cake once all the layers are cooled. I was impatient the first time around, and started stacking warm layers. The frosting started to melt in between the layers and the whole thing started sliding all over the place. Oops.

Vanilla Frosting
1 cup shortening
1 cup dairy-free margarine (I use Fleischmann’s Unsalted Margarine)
7 cups powdered sugar
2 teaspoons vanilla
pinch of salt
1/4-1/2 cup dairy-free milk

1.) Beat the heck out of the shortening and margarine until fluffy and well blended.
2.) Add the powdered sugar slowly.
3.) Add vanilla and salt.
4.) Add the dairy-free milk until the right thickness is achieved.


  1. Kelly @ In Everything says

    beautiful:) Their expressions are priceless:)

    I love this cake, too! I've made it for my son's 1st birthday and my mother-in-laws birthday the following month b/c I loved the way it looked;)

    I cheated though…. I used milk,peanut & egg-free cake mix and then used a can of Sprite;) Mixed it well with a mixer and then divided the batter three ways!! (I used to boxes of mixes, and 2 cans of soda to get the 6 layers)!

    nice to know I can do it from scratch though:)

  2. Emily Hendrix says

    Hi! I am the author of Sophie Safe Cooking, a food allergy cookbook for anyone allergic to any of the 8 most common food allergens. I also have a website where people can build an allergy profile and use them to search for groceries that fit their allergens. If you would like to review my book or website, I would be happy to arrange complimentary access. I look forward to hearing from you.


  3. foodallergychronicles says

    This cake simply took my breath away! My kids would go crazy for a cake like this! I have kept away from food colourings due to my eldest son's eczema. (Felt that he was sensitive to the colour red) Would love to try this cake now that his skin has cleared. Where do you get the gel colours from? I live in Canada. Susan H. @ The Food Allergy Chronicles

  4. Jenine says

    Love this idea! I used to use Wilton gels, but they ALL now have cross contamination warnings for nuts, soy and other allergens….Will regular food coloring work too?

  5. nancy victory says

    I am a mom who is new to having a child with food allergies and has a birthday coming up. Perfect timing can not wait to try this!!!!

  6. says

    I just found this the other day looking for a cake and instantly knew this was THE one to attempt for my daughter’s b-day today! I looked no further. If it comes out 1/2 as good as yours I’ll be pleased. I have very little red so I think my will be pastels. I can’t wait!! :) Thanks you for sharing this treat!!
    Kristine :)


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