Rainbow Cake!
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A delicious and bright rainbow cake with vanilla buttercream frosting, a pink drip and sprinkles!
Rainbow cake
Oh hellooo most requested recipe OF ALL TIME. I am not even joking, this recipe has been requested over and over again and I am ~finally~ posting it on to my blog! It’s taken a fair old time as I wanted to get it right!
I love all things cake, we all know this, but a rainbow cake is something else. The absolutely insanely bright colours, the sweet taste, and all things cute take it to a different level entirely! It is just glorious.
Disclaimer
So… I will say from the beginning that this recipe uses lots and lots of ingredients, and it is a humongous cake! Like, its 6 layers of cake, and all the buttercream in-between the layers, and all the decor on top!
And I will also say from the beginning… YES I KNOW THE RAINBOW HAS SEVEN COLOURS. This cake, is only six. When baking this cake, I just find making 6 colours so much easier, and you can see the obvious differences. I am not bothered about the seventh!
Red, orange, yellow, green, blue and purple… the main colours you need in your life. I did slightly compensate for the lack of seven colours by adding in a pink drip on the outside but we will get to that later.
Sponge
For this cake, I did make probably the biggest one tier cake ever. It’s about 8-9” in height, and uses so many ingredients. Because it is a six layer cake I decided to make it in two batches. So three layers at a time, so therefore you still only need three tins!
I made the cake a 600g mix, so that it’s super easy to split into two batches. The best way is to weigh 5-6 medium eggs, and get as close to 300g as you can, for example 312g, and then match the butter, sugar and flour to that weight.
Colour
Then, you mix it all together like normal, and then split into three bowls. It doesn’t matter which colours you do first, but I did red, orange, and yellow together, and then green, blue and purple.
The oven temperature is a bit lower than normal, as I don’t want the sponges to brown too much. This also comes somewhat from the brands of colours that you use! Red food colouring, orange food colouring, yellow food colouring, green food colouring, blue food colouring and purple food colouring. for the sponge mixtures!
Buttercream
Once my sponges are baked, I leave them to cool completely and freeze them wrapped in clingfilm over night so that they are easier to decorate the next day – but this bit is completely optional of course!!
For the buttercream, you do use 750g unsalted butter and 1500g icing sugar, which technically is a little obscene but the amount of servings from this cake is huge so please don’t be a negative Nelly about the sugar content!
I make my buttercream like normal by beating room temperature unsalted butter on its own for several minutes to make it really loose and supple, and then I gradually add in the icing sugar! I make sure to beat this for quite a long time.
White food colouring
You can do several methods to get whiter buttercream, by beating the butter on its own for a lot longer, or using a smidge of purple buttercream to counter act the yellow, but I love using this white food colouring! It looks amazing on my white chocolate drip cake and I haven’t looked back since.
I add a little at a time and keep beating it very well to make sure its really white and bright to contrast against the colours of the sponge! Making the buttercream whiter is completely optional of course though.
Decoration
When I am starting to decorate the cake, I dollop a few tablespoons of buttercream onto each sponge and smooth over, making sure to get the order of the colours in the sponges correct of course…!
Once you have layered each sponge you need to do a crumb coat by using as little buttercream as possible around the edges to seal in the spare crumbs from the sponges! I then chill the cake for a while to firm it up before adding another layer of buttercream on top.
I use a large metal scraper to decorate the sides of the cake, and a small angled spatula to also help cover the sponges – and its much easier and you are going to get a smoother finish using these as well!
Sprinkles and drip
Just as I have finished the buttercream I carefully press in some rainbow sprinkles to the bottom of the cake for a bit of colour and I just love the design – be warned, sprinkles will fall off at this point so beware! After this, I chill the cake again!
For the pink drip, I use white chocolate ganache with this pink food colouring added in. Its a super bright colour so you don’t need add too much and it means you get the best coloured drip ever!
Finishing touches and tips
I then pipe on the leftover buttercream and add on some more rainbow sprinkles and the best cake ever is finished! I am in love with the sponges and how bright and pretty it is – but the key point to make, YOU NEED TO USE GOOD QUALITY COLOURS.
Using supermarket colourings, will NOT work as well, or maybe at all… so please don’t waste ingredients by doing this! The colourings are 100% worth the investment as they last for so long! Any questions, leave them below in the comments and happy baking! x
Rainbow Cake!
Ingredients
Cake
- 600 g eggs (weigh eggs in shell) (about 10-12 medium eggs)
- 600* g unsalted butter
- 600* g caster sugar
- 600* g self raising flour
- 1/2 tsp red, orange, yellow, green, blue, purple food cololuring
Buttercream
- 750 g unsalted butter (room temp, not stork)
- 1500 g icing sugar
- 1 tsp vanilla extract
- 1-2 tsp white food colouring
Decoration
- 180 g white chocolate
- 75 ml double cream
- 1/2 tsp pink food colouring
- Rainbow sprinkles
Instructions
For the Cake
- Preheat your oven to 160ºC/140ºC fan and line three 8"/20cm springform tins with parchment paper and leave to the side for now.
- Weigh 5-6 medium eggs in their shells and get as close to 300g as possible (e.g. 312g)
- Then add 312g of butter and caster sugar to a bowl and beat until light and fluffy.
- Add in the eggs, and 312g of self raising flour and beat again until smooth.
- Bake the cakes in the oven for 30 minutes (or until baked - test with a skewer).
- Once baked, leave the cakes to cool in the tin for 10 minutes before removing to a wire rack to cool fully.
- (You can wrap the sponges in clingfilm once they have cooled and freeze over night to make decoratin easier but this is optional!)
Buttercream
- Once all of your cakes are cooled, you can make the buttercream.
- Beat the room temperature unsalted butter on its own for a few minutes to soften it and make it supple.
- Gradually add the icing sugar beating very well each time until its all mixed in.
- Keep beating and add the white food colouring and vanilla extract and beat for a few minutes.
Buttercream Decoration
- Using a 10" cake board, add your first sponge. I start with purple as its the bottom colour.
- Add a couple tablespoons of the buttercream on to the sponge and smooth over. Repeat this with blue sponge, then green, yellow, orange and finally red at the top.
- Using a small amount of buttercream, smooth over the sides of the cakes and fill in any gaps and create a crumb coat.
- Refrigerate or freeze the cake on the board for an hour or so to chill and firm to make the next stage of decorating easier.
- Once chilled, add on lots more buttercream around the sides of the cake with a small angled spatula, and smooth over using a large metal scraper until the sides of the cake are smooth like in the photos!
- Carefully press some of the sprinkles into the bottom of the cake using the palm of your hand to create the sprinkle effect!
- Once this has been done, refrigerate again whilst you make the drip!
Decoration
- Add the white chocolate and double cream to a bowl and heat in a microwave in short 10 second bursts stiring well each time.
- Once melted and combined, add the pink food colouring and mix until smooth!
- Add the pink ganache to a piping bag and carefully cut off the end and drip down the sides of the cake. The more you push over the side of the cake with the piping bag, the further it will drip!
- Add the leftover buttercream to a piping bag with your favourite piping tip and pipe swirls of buttercream onto the top of the cake (like I have done in the photos)
- Finally sprinkle on some etra sprinkles and leave the cake to set in the fridge fully.
- In the hot weather I store the cake in the fridge until it has been portioned.
Notes
- This cake lasts 4-5+ days once made!
- The colours that you use and what order are up to you, this recipe is just how I did it! You can swap up the order or whatever you prefer!
- You should avoid supermarket colours as they are not strong enough.
- In this recipe use:
ENJOY!
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J x
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Apologies In advance, because I HATE reading these kind of questions… but if you were to do it in 6 inch tins, would it be ache to hold itself up? Just thinking I’d love to make it but I’d have nowhere near enough people to eat one this big. Sorry again, I know you’re not here to make recipe adaptations, just curious if a 6 inch 6 layer cake
I would maybe use a central dowel for a 6″ one as it is less in diameter!
Hello,
How long do you need to leave it after decorating frozen till you can eat it? Thanks! Love all your recipes! !
By the time you have decorated it and left it in the fridge etc etc it should be fine to eat – depends how long you freeze the sponges for as that is an optional part of the recipe.
My daughter has been asking for a rainbow cake for a while so when I saw your recipe I thought I’d give it a go! Cake turned out perfectly and the recipe was super easy to follow. My daughter loved it thank you so much for the recipe 🙂🙂
Hi Jane,
I’m new to freezing cakes. Do you recommend keeping the cake in the fridge once it’s decorated? And will the icing be ruined if the cake is defrosting? (Sorry if thats a silly question, I’m always hesitant!)
Generally I don’t keep cakes in the fridge unless there is a fresh topping – but the cake would be fine in the fridge before it’s portioned, afterwards it will dry out. And freezing of the sponges is optional as mentioned on the post, you can just chill them for a bit.
This recipe looks great! Im looking at doing a 4 layer drip cake! In a 8inch tin would this be enough for 4 layers?
This recipe is in 8″ tins already – so do you want to do less mix? I’m not sure what you mean sorry.
Hi Jane
Is there any way to make this cake gluten free?
Always worth trying gluten free alternatives and maybe xantham gum!
Hello! When I used colouring previously in sponges I always struggle with it baking properly and it being to wet and dense. Any suggestions on how to avoid this?
Thank you
Use the colours I have recommend and linked as I do not experience this!
Hi Jane! This cake looks amazing 🤩 I always seem to struggle with the drip and I wonder if it could be the type of white chocolate. Is there a type or brand that you would recommend? Thank you!
Hey, I use Callebaut chocolate for drips xx
Can’t wait to try this for my daughters birthday next week, it looks amazing!
Can I ask which food colours you used. I’ve found in the past that If you need to add quite a bit of colour it makes the cake taste nasty.
All of the exact colours I use are linked in the post and on the recipe notes! I hope you love it!! x
After taking the cakes out of the freezer how long do you leave them before decorating?
I decorate from frozen – I don’t thaw them!!
Hi, this looks amazing, I can’t see anywhere the make of the food colouring you use, could you please let me know which make you use.
Thanks
Amy
They all are linked on the post, and in the notes!
I’d like to make this as a 4 tier as 6 will be too big, so I’m not sure of the ingredient measures
Thank you
Which brand of food coloring do you recommend?
They all are linked on the post, and in the notes!
Hi Jane! I love your recipes! Excited to make this one for my daughter’s first birthday! Question- can I refrigerate the sponges instead of freezing it a day ahead of doing the buttercream icing? If I did freeze them how do you recommend defrosting them for decorating?
Ahh yay!! I just decorate from frozen – I don’t thaw the sponges and I find it much easier! You can refrigerate them instead though but only for an hour or two to make it easier to decorate! x
Wow this rainbow cake looks like the dream!!! Might make this for my little girls fifth birthday! What rainbow sprinkles did you use?
I got these particular ones from America so you can’t get them easily, but its worth a google!!
Hi Jane,
I made a celebration cake last week with a white chocolate drip. I turned to your recipes (as I always do) for all the elements of the cake. The drip was just white chocolate in one of your other recipes, no oil or cream added and I think you wrote it’s something to do with white being a different consistency to milk and dark. In this recipe though you do use cream. Can you tell me why? I’m trying to perfect my drip with every cake I make. Thanks!
I do various different types of drip, but I wrote that on that post because often people will just straight swap the chocolates which doesn’t work! Either method works, but this one works quite well when adding colour!