Rainbow Cake with Fluffy Vanilla Buttercream (Allergy-Free and VEGAN!)

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The new school year is here, and it’s been off to a rough start. But it’s okay! Because God is good and sovereign.

This cake was part of an allergy-free birthday cake that I made for two twin boys who turned six back in June. It’s amazing how moist the cake is without typical cake ingredients such as eggs and butter (I didn’t have a slice of it but I was able to eat the shavings I made when I trimmed the cake!)! I think there’s something about the soy milk and vinegar that acts as a thickener, but don’t trust me on that. I’m terrible at science.

The cake recipe below is double the original version. I doubled it because the cake batter looked too thin for me in the cake pans, and I wanted a thicker bottom tier anyway. And instead of making 6 layers, I made five, taking out the purple layer. Since I only had two cake pans, I had to keep reusing the pans, so I cut out 5 parchment paper rounds and resprayed the pan each time. It’s a bit of a hassle, but it’s okay since you can make this entire cake easily by hand with a whisk…so I guess it all evens out =).


Allergy-Free/Vegan Rainbow Cake
Adapted From Speed Bump Kitchen
Makes one 5-layer 9-inch cake


5 1/2 cups all-purpose flour
1 tablespoon baking powder
2 teaspoons baking soda
1 teaspoon salt
4 cups dairy-free milk + 4 teaspoons vinegar, set aside to thicken
3 cups white sugar
1 1/3 cup oil
2 tablespoons vanilla

1. Preheat the oven to 350. Trace your pans onto some parchment paper, and cut out 5 rounds. I used 9-inch cake pans.

2. Whisk together the flour, baking powder, baking soda, and salt in a big bowl. In another large bowl, mix together the thickened dairy-free milk, sugar, oil, and vanilla together.

3. Add about half the wet into the dry ingredients, and beat. You want to get rid of the lumps or they’ll stand out against the colored cake. Add the second half of the liquid and fold in gently.

4. Using a scale, divide the batter into 5 equal portions. You can do this by tare-ing a big empty bowl, adding the batter to determine total batter weight, dividing the total weight by 5, and measuring out 5 portions to color.

5. Add enough of each color of food coloring (I use gel food coloring) to each portion and stir until desired shade is achieved. Transfer each color to an individual cake pan that has been lined and sprayed with cooking spray. If you don’t have enough pans, you will have to keep reusing them. Don’t worry, these cakes bake quickly.

6. Bake for 10-12 minutes, until the center is set. Remove the cake from the pan to a cooling rack (you may have to let it cool down for about 5 minutes or so), add a new parchment circle to the pan, re-spray, and bake the next layer.

7. Once all the layers are cooled, you can frost and build the cake. I used the vegan buttercream frosting that is posted right below!


Vegan Vanilla Buttercream
From Speed Bump Kitchen
Makes about 8 cups


1 cup shortening
1 cup dairy-free margarine (I used Earth Balance Buttery Spread)
7 cups powdered sugar
2 teaspoons vanilla
pinch of salt
1/4 cup dairy-free milk

1. Beat the shortening and margarine until light and fluffy.

2. Slowly add the powdered sugar. Add the vanilla and salt.

3. Add the dairy-free milk until the desired thickness is achieved. Don’t add too much or the frosting won’t be thick enough!


Here’s the final result of the entire birthday cake! The rainbow cake is on the bottom tier.


P.S. All photos from this post are from the extremely talented [Auntie] Vinnie Y!! Please check out her Facebook page and blog! =) Thank you for the amazing photos that made everything so much better!

Until next time,

Soli Deo Gloria, and Happy reading, eating, and baking!