Rainbow Layer Cake

Slicing the cake

Unless you have been living under a rock you have seen photos of these rainbow layer cakes popping up all over the place. But have you tried baking one yourself? I decided it was time to give it a go and made one for my beautiful one year old baby girl for her birthday party. I cheated a little and used packet cake mix because I had two cakes to design and bake for the party and didn’t have time to be fiddling around with recipes.

I used 3 cake mixes dividing each one into two before colouring them to make 6 layers. Apparently paste or gel colouring will get a stronger colour and you can use natural colourings but the colours will not be as bright. I just used liquid food colouring from the supermarket. I used a clean and dry egg shell to mix the colour before adding it to the cake mix. You only need four colours – red, blue, yellow, green, you can then mix them together to create your rainbow.


Rainbow colours


      • Pink/Red
      • Orange – 1 red drop to 2 yellow drops
      • Yellow
      • Green
      • Blue
      • Purple – 3 red drops to 1 blue


You could also make the following colours depending on your colour scheme:

      • Dark Green – 1 red, 4 blue, 1 yellow
      • Lime Green – 3 yellow, 1 green
      • Aqua – 4 blue, 2 green
      • Orchid – 5 red, 1 blue

Add your colouring slowly until you achieve the desired colour. You can always add more colouring but once its in that’s it. Make sure you give it a good mix between adding colour to see the proper result. Also keep in mind what cake mix you are using. Some mixes are very yellow to begin with and this will effect the outcome of your colouring. For the brightness of my colours I used approximately 5-10 drops of colour per half cake mix.

I kept a close eye on the oven to be sure my little half cakes didn’t burn and was pleasantly surprised by how the colours turned out. They were a lot brighter after baking but were within a nice pastel range of colours.

After the cakes were cooled I layered them with baking paper and popped them into containers to keep fresh over night. Then came the layering.

First I mixed up a lot of icing – enough to use between each layer and cover the outside of my 6 layer tower. I wanted something light and fluffy and white as I could get it. This is the recipe I used:

    • 170g Butter, softened
    • 750g Icing Sugar
    • 90ml Milk
    • 4tsp Vanilla (optional)

I whipped the butter until it was very pale, then whipped the icing sugar into it until it was really light and fluffy and pale. To make sure I could get it as white as possible I also omitted the vanilla essence, but you could add that in if you don’t mind the colour.

Cutting layer cake

To avoid accidentally mixing any cake crumbs into my icing mixture I separated out a few scoops at a time into a separate bowl and used this to ‘dirty ice’ the layers together. I trimmed the top off each cake to make it nice and flat and then covered it in a layer of icing before adding the next layer. As I went I tried to make sure it was as level as possible and if it looked a little crooked I just added a little extra icing to even it out.

Layering the colours

Once all six layers were done I covered the whole cake in a thin layer of icing and left it for about 20 minutes to ‘set’ before doing a final clean layer of icing all over. I heated my palette knife in hot water and dried it before using it to smooth the icing. My tip is to smooth the top of the cake first, then do the side in one continuous sweep.

top of layer cake

To decorate I cut a number 1 from paper and placed it on the top of the cake and sprinkled hundreds and thousands all over the top, then removed the paper. I printed mini bunting flags to match the party decorations and taped them to a piece of tooth floss that I strung between two skewers. Add a candle and ‘ta-da’, a beautiful big cake with a surprise rainbow layered centre.

Rainbow Layered Cake

Of course the big moment came when I cut that first slice and slowly lifted it out. I was so happy that it worked and looked fabulous and was a wow moment for everyone at the party. I was worried that there would be too much icing, but I was pleasantly surprised, it was just right.


We also had a Princess Dolly Varden Cake at this party and a giant cupcake smash!

You can even read all about the party, the decorations and the games.

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