Week 95: Rainbow birthday cake

 It has been so many rainbow cakes since the very first time I made one of these. And I think this is definitely one of my favourite “celebration cake”, just because the colours are so vibrant, and despite what I always thought, it really doesn’t taste half bad either.

I am using the same rainbow cake recipe as I have always used, but, this time cutting it by half to make a 6-inch cake. And I think I have found a better, at least for me, way to make this cake, with minimal tools and washing.

Makes a 6-inch round cake


113g unsalted butter, at room temperature

213g caster sugar

80g egg whites, at room temperature

1 tsp pure vanilla extract

213g plain flour

2 tsp baking powder

1/4 tsp salt

3/4 cup whole milk

Red, orange, yellow, green, blue and violet color gels

2 tsp gelatine powder, bloomed in 2 tbsp cold water

60g icing sugar, sifted

480ml heavy cream, very cold

1 tsp pure vanilla extract

1 tsp vanilla paste


1) Measure and record the weight of the stand mixer bowl.

2) Put the unsalted butter and caster sugar into the bowl of a stand mixer, and mix on high speed using the paddle attachment for about 5 minutes until mixture is light and fluffy.

3) Add the egg whites and vanilla extract into the mixer bowl and mix until well-incorporated.

4) Measure flour, baking powder and salt into a separate bowl. Sift half of the flour mixture into the butter mixture and fold by hand to wet the dry ingredients.

5) Pour the milk into the mixer bowl, and sift in the remaining flour mixture. Fold lightly to incorporate, and turn on the mixer on medium for about 10 seconds so you get a homogeneous batter.

6) Measure the weight of the stand mixer bowl with the batter, and subtract the original weight to get total weight of the batter. Then, divide this by 6. I got 135g for each cake layer.

7) For the following, get ready 2 6-inch cake tins, 2 baking strips, 6 6-inch round grease-proof paper, a bit of vegetable oil for greasing the cake tins, 2 medium bowls (to color the cake batter), some paper towels and a generous roll of cling wrap.

8) Preheat oven to 175C fan and soak the baking strips in cold water.

9) Measure the first portion of batter into a bowl and add the violet coloring. Fold by hand to color the  batter evenly.

10) Grease and line the first cake tin with the prepared paper round, and scrap the violet cake batter into the tin. Put the baking strip around the cake tin, then bake in the pre-heated oven for about 12 minutes. The cake is ready when it starts to pull away from the sides.

11) While the first cake layer is baking, prepare the second cake layer using the second bowl and cake tin. Alternate this as you bake.

12) Once you remove a cake layer from the oven, remove the cake strip to be soaked for the next use. Unmould the cake layer immediately and wrap it in cling wrap and freeze.

13) For the frosting, start by putting the whisk attachment into the freezer to chill. Then, melt the bloomed gelatine powder in a bain-marie, making sure it is properly melted. Leave in the bain-marie with the heat turned off.

14) Add the icing sugar and cold heavy cream into a clean mixer bowl, fitted with the chilled whisk attachment. Whisk on high until cream has reached soft peaks.

15) Mix the melted gelatine with the vanilla extract and paste, then, scrap into the heavy cream mixture while whisking is running. Mix for a few seconds more until stiff peaks. Make sure not to overwhip.

16) Scrap frosting into a large bowl, cover with cling wrap and allow to chill overnight so it is nice and firm for the cake assembly the next day.

I have to work in a limited workspace with limited tools, so, the above method works best for me. Of course, if you have enough bowls and baking tin, and a huge oven, it would be a lot simpler for you. Since the cake layers are so thin, it is very important to use a cake strip so you end up with even layers. The frosting is enough for rather generous layers between the cakes and to cover the entire cake nicely. For this cake, I used some dark chocolate glaze to cover the top of the cake and for some side drizzles. There is just something about the chocolate drizzles that makes it just that bit more tempting.

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