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Rainbow Pop Celebration Cake

by Alan Keely & Gary Keely from Cereal Killer Cafe Cookbook

Want to make a showstopping Rainbow Cake? This easy recipe walks you through the process step by step to achieve brilliant results. Perfect for birthday parties.

From the book

Alan Keely & Gary Keely


There’s no better way to celebrate a friend’s birthday, failing a job interview, or getting divorced, than with a showstopper of a cake. And I think this cake, with its twist on the classic Rice Krispie square, is worthy of a Great British Bake Off semi-final! I’ve often found there are a lot of missed opportunities when it comes to celebrations; here are a few unheard-of days you should probably start celebrating, right away.

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35g unsalted butter
245g white marshmallows
Several food colourings – red, orange, yellow, green, blue, indigo, violet
280g Rice Krispies
For the frosting:
300g unsalted butter
1 x 454g or 2 x 213g tub marshmallow fluff
500g icing sugar
Hundreds and thousands, to decorate

Essential kit

You will need a 2cm round cake tin.


OK, each layer here needs to be made separately, so melt a large knob of butter (5g) and 35g marshmallows together in a pan with 1 teaspoon of food colouring. Make sure you get the good food colouring from the baking store, as the ones from the supermarkets are good but might not be as vibrant and will tone down the scale of the celebration – meaning less presents.

Add 40g Rice Krispies and mix well. Press the coloured cereal into a 22cm round cake tin with the back of a metal spoon. This can be quite messy as the marshmallow is very sticky and has the consistency of spider webs, so cover the mixture with baking paper before smoothing over the paper. Repeat this process with every colour of the rainbow. If you have only one cake tin you can keep the layers separate with pieces of baking paper. Make sure you keep the layers in the fridge as you make each one.

To make the frosting, beat the butter with an electric mixer until soft, then add the marshmallow fuff and beat further. Next, add half of the icing sugar and mix until smooth, then add the remaining icing sugar. Use a small amount of the icing to cement the layers together; remember to do them in the correct order according to the colours of the rainbow. That is not the rhyme: ‘red and yellow and pink and green, purple and orange and blue, I can sing a rainbow, sing a rainbow, sing a rainbow, too’, ’cause these are not the correct colours. This is one of the frst things we learn in life which isn’t true, and this is why we have trust issues! The correct order is: red, orange, yellow, green, blue, indigo, violet (Richard of York gave battle in vain).

Once you have built your cake, spread the frosting over the top and sides of the entire cake but leave some to add to your piping bag to fnish off. If you need to smooth the frosting you can run a metal knife under very hot water, dry it with a cloth and use the back to smooth it down. Finish off by piping the remaining frosting around the corners and decorate with wee swirly bits. Scatter some hundreds and thousands, because once I presented this and was asked why I had made a mashed-potato cake!

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