Giant rainbow cupcake recipe

(119 ratings)

Our giant rainbow cupcake is full of brightly coloured, delicious sponge that is sure to surprise. The perfect birthday cake with a light sponge too

Preparation Time50 mins plus 2 hours cooling time
Cooking Time45 mins
Total Time1 hours 35 mins plus 2 hours cooling time
Cost RangeMid

This giant rainbow cupcake is one to try when you want to impress. Unlike other giant cupcakes, this recipe doesn't need a special mould - you simply carve the layers by hand which takes a little time and patience. A whopping 9 layers make up this amazing cake - you could even flavour each layer to match the colour if you want to mix things up. Covered with a homemade buttercream and surrounded by a sprinkling of skittles - watch the kids’ faces light up with delight when they see this amazing cake.

Like this? You'll love our classic rainbow cake made by Bake Off's Candice Brown!


For the cake:

  • 510g caster sugar
  • 510g softened butter
  • 510g self-raising flour
  • 9 eggs
  • 7½tbsp milk, room temperature
  • 3tsps vanilla extract
  • 2¼tsps baking powder

For the reduced-sugar buttercream:

  • 480ml milk
  • 120g plain flour
  • Pinch of salt
  • 220g vegetable fat
  • 220g unsalted butter
  • 440g caster sugar
  • 2tsp vanilla extract
  • Rainbow food colours

For the decoration:

  • 3 packets of chocolate fingers or Kitkats.
  • Rainbow sprinkles
  • Coloured sweets to decorate

You will also need:

  • 3x 7inch sandwich tins
  • Greaseproof paper
  • Piping bag with a star tip
  • Bread/sharp knife for carving




  1. For the cakes:
    1. Preheat the oven to 180°C/350°F/Gas Mark 4 and grease and line the cake tins. You need to make 9 separate coloured sponges so you can reuse 3 tins 3 times or whatever suits the number of tins you have.
    2. For 3 tins worth of mixture, divide the ingredients in 3. Cream 170g of the butter and 170g of the sugar until light and fluffy. Add one egg and roughly a third of the 170g of flour and beat; repeat until all the 3 eggs and flour have been mixed. Add ¾ of a teaspoon of baking powder and mix. Add a few drops of vanilla and mix again. This should give you 660g of batter. Divide the batter into 3 bowls and colour.
    3. Bake in the oven for 15 minutes. Remove and cool in the tins for 10 minutes before turning out onto a wire rack. Repeat twice more until you have 9 layers of coloured sponge.
    4. Wrap the sponges individually in cling film and pop in the freezer for 1 hour. This makes the sponge easier to carve.
    For the buttercream:
    1. Whisk the flour and salt into the milk in a small saucepan and heat gently over a low heat until you have a smooth ball of mixture. Don’t worry if it has lumps, just pop it through a sieve. Leave it to cool, then pop it in the fridge for half an hour
    2. Beat the other ingredients together in a large bowl with an electric whisk until light and fluffy. When the flour mix is cold, add it to the rest of the ingredients spoon by spoon, continuing to beat the mixture with the electric whisk while you drop it in.
    3. Beat for a few minutes until smooth and shiny. If you can still feel the sugar when you test a bit you’ll need to beat some more and keep beating until it’s smooth and has the texture of whipped cream.
    To assemble and decorate:
    1. Cut a 6'' and 5'' circle from greaseproof paper.
    2. Stack the 4 bottom coloured sponges in the opposite way you would like them to display – with the bottom colour at the top. Place the 6'' circle on the top of the sponges and cut away from the edge of the circle in a diagonal line to the furthest outside edge of the cake to get the curve of the base, this is called tapering. Flip the sponges so the smallest one is now at the bottom and sandwich together with a thin layer of raspberry jam and buttercream.
    3. Place the top 5 sponges in the order you would like them to display (no need to flip here) and repeat the process with a 5" circle. Sandwich the two sections together with raspberry jam and buttercream.
Top Tip for making Giant rainbow cupcake

Don’t throw the trimmed sponge away, you can make rainbow cake pops or just have it with custard.

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Victoria Threader
Recipes Writer

Victoria Threader is 'the queen of cupcakes' and a contributing Recipe Writer at GoodTo. Not only can she bake delicious cupcakes, she can decorate them too - with each of Victoria’s cupcakes topped with handmade edible toppers. Some of her most popular cupcakes include: rainbow cupcakes, hidden shape cupcakes and even giant cupcakes.