Updated: Jun 5, 2020
A couple of weeks ago I was asked if I could make a cake in the shape of a rainbow with layers of rainbow coloured sponge cake inside. I had seen rainbow layer cakes before but these had generally been round or square layers of cake piled on top of each other. I had never seen one in the actual shape of a rainbow. Of course, I could have made life easy and baked seven layers of sponge in a round cake tin and then cut them all in half, sandwiched them together and stood them all on the flat side so that they formed a semi-circle, but where would be the fun in that?!
I love to try and push my boundaries a little sometimes and I had recently been watching a video on the use of lighting and mechanics in cake so I thought it would be a great idea if
I could incorporate some flashing lights somewhere. After a quick search on the internet I found these wifi remote controlled LED strip lights, and so the rainbow cake with multi-coloured flashing lights was conceived. These lights are super cool as they have a self-adhesive backing and you can cut them to the length that you need, but what you cut off is not wasted as there are connecting pins on the other end as well so the remainder can be used another time. You can also buy connectors to put in between two strips so your cut sections can be used again and again. Awesome!
Having found my lights, I then needed to build a structure to support the cake so I made an arc out of cardboard and then covered it in aluminium foil to make it food safe. I briefly toyed with the idea of just sticking the lights around the cake board as that would have been easy but this was never really a serious option as I wanted my rainbow to light up on the inside. The self-adhesive backing on the light strip was perfect for this as I was able to cut the strip to the right length and stick the lights around the inside of my cake support structure. The battery operated control box was also just the right size to fit neatly inside so that all the working parts were kept away from the actual cake to prevent any possibility of someone eating them accidentally.
Having sorted out the technical side of things, I then needed to bake the cake so I set my mixer to work and once the cake batter was prepared I needed to split the mix into seven separate bowls, each one carefully weighed so that they all contained the same amount of batter. These were all then coloured a different colour of the rainbow and baked in strips so that I
could layer them up around my cake structure that I had previously prepared. Five of the cake strips needed to be cut in half and placed on either side of my arc structure and a layer of buttercream spread in between each layer. I used white buttercream for this so that the colours would really pop when the cake was cut.
Once that was done the whole thing needed to be given a crumb coat of buttercream and carved into the right shape for the rainbow.
Then it was out with the seven mixing bowls again to colour up seven different batches of buttercream for the outside of the cake and boy did this cake take a lot of buttercream! When I had all the colours mixed I needed to pipe the stripes of the rainbow on both sides of the cake, being careful to get them all in the right order.
I attached flower paste cloud shapes in front of the arc in the middle to hide the lights and control box and decorated the cake board and I used marshmallow fluff as an adhesive to stick on some white marshmallows to represent clouds. Then I covered the rest of the board with coconut pieces and sprinkled on a few sugar pearls and hundreds & thousands to break up the whiteness and fit in with the rainbow theme. After that, all that was left to do was to place a ribbon around the cake board and, voilà! The rainbow cake with multi-coloured flashing lights was complete.
I had lots of fun making this cake and I hope you like it. If you would like a free, no obligation quote for your own custom made celebration cake or have any questions then please feel free to contact me here, email email@example.com or private message the Facebook page. Subscribe for all out latest news and offers direct to your inbox.
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