Rainbow Surprise Cake


This cake was inspired from a conversation with a new I met from a baking school. With so much that’s going on we wanted to do our small part to brighten up someone’s day. The theme is to tag a friend, share a message, and we would pick one winner at the end of the week and deliver a sweet treat. Even if they didn’t win, we felt that just the thought that your friend is thinking of you and sending a message would be nice! 

To create the hidden Rainbow surprise effect, I used a Bundt cake tin, a vanilla cake recipe and created coloured layers in rings. When you slice through, you get this gorgeous rainbow inside! You can use any 5 colours you’d like for the rainbow, and make sure to use a white cake recipe, so that the colour stands out even more. A combination of real and imitation vanilla gives you the nostalgic classic vanilla cake aroma, that is so simple but lovely. In this recipe I followed, Buttermilk by Sam also provided a video in her Instagram highlights you can check out 🙂 

Here’s also a great trick for removing your bundt cake easily from a bundt pan (especially if you use one with lots of nooks and crannies!). I found that coating with butter and almond flour (or any nut flour) worked well! 

Hope you enjoy making this cake, and hope we share some smiles in the process!! ☺️🌈🌈🌈

Rainbow Surprise Cake
Makes 21-cm Bundt cake

Rainbow Surprise Cake
adapted from Buttermilk by Sam

For Vanilla Bundt Cake
260g all purpose flour
100g cake flour
227g butter
1/6 cup refined coconut oil
1/6 cup vegetable oil
1 3/4 cups sugar (reduced)
1 teaspoon salt
2 teaspoons pure vanilla
1 teaspoon imitation vanilla
2 teaspoons baking powder
4 egg whites, at room temperature
1 cup buttermilk, room temperature
Food colouring (preferably gel)
Almond flour (for coating the pan)

For Vanilla Icing Glaze:
1 egg white
~200-300g icing sugar
Vanilla extract
1-2 tablespoon milk

To make Vanilla Bundt Cake

Preheat oven to 325 deg F or 160 deg C. Butter and coat a large bundt pan with almond flour (this helps to release the cake easily later! Sift together the all purpose flour and cake flour into a bowl. Set aside.

Cream butter, coconut oil, vegetable oil and sugar together for at least 5 minutes, until very light and fluffy. Add salt, vanilla extract, and baking powder and whip for a few more minutes. With the mixer on, add egg whites, one at a time, allowing each to be fully incorporated before adding another. 

Add half of your flour mixture, and mix until just combined. With mixer on low, add buttermilk in a slow drizzle. Add rest of flour and beat just to combine.

Technique: In 5 separate bowls, add about 4-5 tablespoons of batter. Using gel food colouring add red, yellow, green, blue and purple to each bowl and stir to combine the colours. Use about 2/3rds of the remaining batter to fill your bundt pan. Leave the last third aside. This will be used to cover the rainbow.

Fill a piping bag with red batter and make a circle within the bundt on top of the white batter. Use the back of a teaspoon to smooth out the red batter and even it out by tapping the cake pan on the work surface. Fill a piping bag with yellow batter, and pipe it within the red. Continue with the rest of the colours, until you have a thin circle of purple. Use a spoon to gently add the rest of the white batter on top. Smooth top over with an offset spatula. Mine was enough for a 21-cm / 8.26 inch Bundt cake + a mini 13-cm / 5-inch funfetti cake (as the original recipe was made for a 9-inch cake).

Measurements for my 21-cm Bundt cake: 480g white vanilla batter for the first layer, followed by 65g red, 65g yellow, 60g green, 55g blue, 50g purple, and 200g white vanilla batter to cover the cake. This recipe makes 1260g batter, leaving around 295g for the mini 13-cm funfetti cake. 

Bake for about 45-50 minutes (mine took 50 minutes), checking for doneness after 40 minutes. Allow cake to cool for about 15 minutes in pan, then invert onto a cooling rack.

To make Vanilla Icing Glaze:

Whip 1 egg white until soft peaks. Add in 200-300g icing sugar and whip well until a thick vanilla glaze. Add in 1-2 tablespoon of milk to achieve desired consistency. When cake is cooled completely, drizzle on the vanilla glaze. 

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