Jellybean Rainbow Cake

This cake looks like it was lifted straight from Willy Wonka’s factory, however it is incredibly easy to make. You don’t need to be an experienced baker, all you need is patience. You may have come across this recipe when I shared it before the Irish Constitutional Referendum a number of years ago; I believe in equality for all families in all their wonderful shapes and sizes.

I’ve also shared this recipe to celebrate #PRIDE because I believe that for too long people who do not conform to the norm have not been treated equally, and continue to be discriminated against. We can do better. Pride is an opportunity to reflect on how we can improve as a society.

So if you’re looking for an over-the-top sugar fest for a celebrate, Pride or otherwise, you can’t go much wrong with this one-time Birthday cake which was made for somebody who believes in the power of being included as much as I do. Cxxx

I baked the sponge on the first day and did the first layer of basic icing on the same day. Essentially it’s a victoria sponge recipe based on Delia’s classic, the key is how you colour and bake the mixture. To keep it simple I flavoured every single layer and the frosting vanilla. Trust me, if you’re under pressure for time you will need to keep it simple.

If I had 4 sandwich tins I would have been able to bake it in half the time it took me. I didn’t, I had 2. However this means that it is easier to split and colour the mixture each time. It’s also easier to ensure you organise your colours because some lead onto another etc, etc.

A classic rainbow cake would have 7 layers, this has 8. The reason being that every time I baked a batch of sponge, I baked 2. It would have been rude not to include the final layer.

This is cake is loaded with sugar. It technically serves 20, however you could get more servings out of it because a slice of cake can be halved again. The ingredients cost me approximately €17 in total which means it works out at less than €1 per slice if you’re being generous.

Because this cake is different to the norm, I’m going to write the recipe slightly differently so beware!

You need to repeat the victoria sponge process 4 times in order to come up with 8 sponge cakes.

You will need the following food colourings for the sponge: yellow, red, blue

Ingredients (repeat x 4)

  • 110g Butter
  • 110g Caster Sugar
  • 110g Plain Flour
  • 2 Medium Free Range Eggs
  • 1 teaspoon baking powder
  • 1 teaspoon vanilla extract


  • Mixing Bowl or Stand Mixer
  • Wooden Spoon
  • Weighing Scales
  • 2 Victoria Sandwich Tins (20cm)
  • Baking Parchment (non stick)
  • Scissors
  • Butter & Flour (to grease and dust the tins)
  • Cooling Rack


  1. Preheat your (fan) oven to 170 degrees celcius.
  2. Line the base of your sandwich tins with parchment paper and use the butter and flour to grease the sides, this is very important.
  3. Cut a piece of parchment paper and weigh the flour and baking powder onto it.
  4. Weigh out the butter and sugar together and cream (beat) until light and fluffy.
  5. Add 1 egg and beat until mixed.
  6. Add the second egg and beat until well mixed. If it begins to look curdled add a spoonful of flour.
  7. Pour in the vanilla extract and mix.
  8. Pick up the baking parchment and pour the remaining flour into the mixing bowl.
  9. Beat until all the ingredients are well combined.
  10. Pour half the cake mixture into the first tin, plain no colouring.
  11. Using the yellow food colouring add 1 teaspoon and stir until your batter turns yellow.
  12. Pour the yellow batter into the other sandwich tin.
  13. Bake in the oven for 25 minutes.
  14. Wash and dry your bowl and make another batch of cake mixture.
  15. Note – you slightly need to overbake these sponges as you need them to hold better when you put them together. It’s easier as this way you don’t need cake dowels.
  16. Remove from the oven and leave to cool for 5 minutes in the tin before tipping upside down and removing the tins and then the baking parchment.
  17. Leave the oven on!
  18. Wash, dry, reline and regrease the tins.
  19. This time pour 2 teaspoons of red food colouring into all the batter.
  20. Remove half into 1 cake tin.
  21. Put a further 1 teaspoon of yellow food colouring into the second half of the batter (this gives you orange).
  22. Repeat steps 13-18 above.
  23. This time pour 2 teaspoons of blue food colouring into the batter.
  24. Remove half into 1 cake tin.
  25. Put a further 1 teaspoon of red food colouring into the batter (this gives you purple).
  26. Repeat steps 13-18 above.
  27. This time pour 1 teaspoon each of yellow and blue food colouring into the batter (this gives you green).
  28. Remove half into 1 cake tin.
  29. Pour a further 1 teaspoon of red food colouring on top. You should get a grey colour. If it is quite pale then add another teaspoon of each (red, blue and yellow) to get it darker.
  30. Repeat steps 13-16 above.

That’s it, your baking part is done. Give yourself a massive pat on the back. Keep your baked cake sections apart from one another by cutting squares of baking parchment and placing between each layer on a plate. Do this before they dry out.

To decorate, finally! Please note this is a generous quantity. You may have some frosting left over but if you do pop it into a freezer bag and freeze for another day.

Ingredients (you will make this 3 times)

  • 250g Unsalted Butter (or if a block is 254g use that)
  • 500g Icing Sugar
  • 10ml Milk (wholefat or semi-skimmed is okay)
  • 1 teaspoon vanilla extract


  • 1 large bowl (or stand mixer with whisk attachment)
  • 1 wooden spoon
  • 1 spatula or knife for spreading
  • 1 cakeboard or cakestand


  1. Whisk the butter until light and fluffy.
  2. Add the icing sugar spoon by spoon on a low setting until it is completely mixed in.
  3. Use the milk to soften the mixture if it goes into a breadcrumb consistency.
  4. Add the vanilla extract and whisk for 3 mins.
  5. Spread a spoonful of buttercream on the cakeboard or cakestand before placing your first layer. This will hold the cake in place.
  6. Use the spatula to spread a thin layer of buttercream frosting between each layer of cake.
  7. Once you have the layers in place then spread the buttercream around the side. There’s no need for it to be neat as you’ll be hiding most lumps and bumps with the jellybeans.
  8. Ice the top last.
  9. For the jellybeans I used 4 bags of Lidl own brand jellybeans. There are 13 flavours in this bag. If there were less I might have separated them and put them onto the cake in a pattern.
  10. Think of building a wall. Each line of jellybeans needs to be slightly offset from the next as this increases the structural integrity.
  11. Smear some fresh buttercream onto the spot you’re going to stick the jellybeans before you put them on. That gives you some fresh “cement”.
  12. As it’s buttercream and victoria sponge, this cake will keep for up to 4 days in a cool dry place.

23 thoughts on “Jellybean Rainbow Cake”

  1. WOW! Has she seen it yet? Thats fabulous, my teeth are chattering at the thought of all that sugar

    1. She has. We cut it open last night after singing Happy Birthday. She was over the moon with it before she cut it to see the surprise. A big hunk of the cake went to school today to share with her friends and show the Home Ec teacher. Her BFF’s (best friends forever) have requested it for their Birthdays next year. LOL!

  2. Oh dear not sure if their mums will be thanking you for that!! Looks amazing. I’m going to make a mini one with different shades of pink for my little ones birthday – great inspiration, thanks a million.

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  4. Hi Caitriona,hoping to make this Thursday for my sons Christening on Saturday. I don’t have a cake box so I am just wondering can I just store it in the fridge uncovered? Thanks, hope it works for me!

  5. RIght I’m making this for real in a couple of weeks (1st birthday). My current query is (oh there’ll be more) in order for it to balance, do you need to shave off the top of each of the cakes as in my experience they don’t come out of the tins flat, but raised in the middle?

    1. Because you’re not filling the tins well – they actually bake flat. You’re not going to fill them too high at all! I don’t shave the top off. Ask as many questions as you like. Top tip is to start baking now and freeze each layer, defrost the day before icing. It makes it far easier on you!

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  7. jane Boardman

    Hi Caitriona, planning on making this cake this weekend for my 6 yr olds birthday..just wondering roughly how long it takes to make? Planning on making it the day before, so might bake the sponges in the morning and then ice it that night… Thanks

    1. Hi Jane, the baking doesn’t take too long – indeed it’s quicker if you have more than 2 tins to work with! The main time drain is decorating. I would allow between 2-3 hours for assembly if you’ve a busy household and have to share the kitchen. 😉

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