Giant Rainbow Layer Cake!!


This is a very large, very extra, super delicious and super full of pride cake.

Yes it’s massive and takes a bloody long time to make, but the result was so worth it. I made it for my sister’s 17th birthday and she loved it.

The pictures are a bit crap (what’s new to be honest) as we were celebrating so I didn’t want to be spending hours photographing the cake instead of eating it.




4 Layers – For each layer:

1.5 cups Plain Flour

1/2 cup Caster Sugar

1 tsp baking powder

200ml Soy Milk

70ml Vegetable Oil

1 tbsp vanilla extract

1 tsp of 4 different coloured food colourings (depending on brand, just add enough until you’re happy with the colour)

240g (3 tubes) of sprinkles.



2-3 tub of vanilla Betty Croker icing (yes it’s vegan!)


500g vegan butter

500g vegetable shortening

7 cups icing sugar

2 tbsp vanilla extract

OR (what I did)

1 tub of vanilla Betty Croker icing

250g vegan butter

250g vegetable shortening

3.5 cups icing sugar

1 tbsp vanilla extract


NOTE: You need to work super fast with vegan cake mix for it to rise, personally I made each cake one at a time, making each layer of cake batter when the previous cake was cooling. This obviously took a long time so if you’d prefer to make a huge batch of batter and then separate it to colour each layer, do so but note they cake will not rise as much (unless you’re super fast or have a helping hand!)

  1. Pre heat your oven to 180C.
  2. Mix the dry ingredients together (flour, sugar, baking powder), then in a separate bowl mix the wet ingredients together (oil, milk, vanilla, food colouring).
  3. Combine the wet into the dry, adding more colouring if you wish, mixing very quickly.
  4. Hit the bowl against your work surface to stop the raising agent working too quickly, place into a greased tin, then bake for 25 minutes.
  5. Leave the cake to cool for 10 minutes in the tin, then place it on a wire rack until it’s completely cooled.
  6. Repeat 3 times until you have 4 layers each of a different colour.
  7. Level off each layer of cake so they have a flat top (I just used a sharp knife and my own judgement)
  8. To make the icing, combine the butter, shortening and vanilla with an electric mixer, then add the icing sugar a bit at a time until you’re happy with the taste and texture. (add in the whole tub of Betty Crocker icing and combine if using it!)
  9. To assemble the cake, smooth a layer of buttercream between each cake and stack them until it’s a stable (and large) tower.
  10. I will 100% recommend a pallet knife to apply the icing around the cake, my pallet knife is tiny so it took a while but it worked out fine. I just pushing the icing onto the cake then smoothed it out best I could, it doesn’t have to be neat as you’re going to smother it with sprinkles anyway.
  11. To apply the sprinkles, I simply pushed them on with my hands, I’m sure there is a much easier way to do this, but I just persevered until the whole damn cake was covered. (Make sure you’re prepared to catch the sprinkles that fall off while applying them!)
  12. Add a candle on top and you’re good to go!

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