Double Rainbow Cake

I had been nervous to bake a rainbow cake before now as there are quite a lot of elements and skills involved that I had never put into practice before. Being the perfectionist that I am, I was keen for this cake to turn out as well as it possibly could. In order give myself a fighting chance I spent a few days watching some baking videos online about how to create the perfect layer cake and how to achieve a smooth finish around the outside using buttercream. After doing a little bit of research I was able to gain additional knowledge on the equipment I needed and I was able to pick up a Cake Scraper and a Cake Leveller before making the rainbow cake. I would advise you invest in both of these things if you take your baking quite seriously or are wanting to create a rainbow cake with even layers and smooth edges.

Watching baking videos online actually led me to the recipe for this amazing rainbow cake, I used a recipe by Cupcake Jemma, someone that I am now subscribed to on YouTube and would highly recommend watching if you want to learn new skills or you just want to see some amazing cakes. When I was baking this cake I actually followed her video as if it was a step-by-step tutorial, this made what was quite a big task feel relatively simple as I was able to play or pause the video whenever I needed to. I used her recipe and techniques to build my colourful sponges but decided to take the buttercream in a slightly different direction and add some colour to the outside of the cake to match the sponges on the inside, which was inspired by another one of her videos.

This cake was definitely the most challenging cake I've ever made but also one of the most satisfying to slice open too. I made it for a family member's birthday and I was relieved when the layers were evenly spaced and had kept their vibrant colours. This cake definitely has the 'WOW' factor and I would highly recommend giving it a go if you want to give yourself a fun challenge or just want to create something special for a loved one.

Cake Ingredients:

9 tbsp – Whole Milk

1 ½ tsp – Vanilla Extract

6 - Concentrated Food Colour Pastes

750g – Unsalted Butter

750g – Caster Sugar

9 – Large Eggs

750g – Self-raising Flour

Buttercream Ingredients:

400g – Unsalted Butter

900g – Icing Sugar

6 tbs – Whole Milk

1 tsp – Vanilla Extract

• Into a measuring jug measure out 9 tablespoons of whole milk and 1 ½ teaspoons of vanilla extract, you will then need to divide this mixture by 6 (which is 1 ½ tablespoons) and pour it evenly into 6 mixing bowls. Once you have picked 6 different colours, add the food colouring to the 6 portions of milk and stir well using a mini whisk or a metal spoon.
• Add 750g of unsalted butter (room temperature) and caster sugar to a stand mixer and mix on a high speed until light and fluffy, this should take roughly 6 to 7 minutes.
• Crack 9 eggs into a small mixing bowl and lightly whisk (similarly to how you would whisk if you were preparing an omelette or scrambled eggs). Whilst your stand mixer is set on a low speed gradually add the eggs to the butter and sugar. Once all of the eggs have been added set your mixer to a medium/high speed for approximately 2 minutes.
• Sift your flour into the stand mixer and gradually mix on a low speed until all the flour has been added and fully incorporated.
• Divide the cake batter evenly into the 6 mixing bowls that contain the milk and food colouring that you prepared earlier. Using a metal spoon carefully fold the coloured milk into the cake batter.
• Now that you have 6 differently coloured portions of cake batter place each one into a lined and greased 8 inch baking tin and bake for approximately 25 minutes or until a cocktail stick comes out clean. I only had two baking tins so I did this step 3 times, so don't worry if you also only have two tins, it is still do-able, it just takes a little bit longer.
• Once all of the cakes have fully cooked and cooled you can now trim your cakes to ensure each layer is the same thickness and size. To do this, I used a cake leveller to slice off the very top of each cake. I then placed a 7 inch cake board onto the top of each layer and used a knife to trim around the circumference of each of the coloured sponges. This will create a smooth surface area for when you are applying your buttercream.
• It's now time to make the buttercream, to do this you will need to mix all of the unsalted butter in your stand mixer until pale and fluffy (this should take about 5 minutes), then add sifted icing sugar in two stages, mixing between each stage until fully incorporated.
• Gradually add the milk and vanilla extract into the stand mixer whilst it is on a low speed, once all of the milk has been added you can beat the mixture at a high speed for a further 2 minutes.
• Using the uncoloured butter cream you can begin to stack your layers, begin by placing your first layer onto a cake turntable and apply an even layer of buttercream onto the top, repeat this process for all 6 layers before applying a crumb coat to the outside and top of your cake. To apply a crumb coat use a small amount of butter cream to completely cover your stacked layers (I used a pallet knife to do this).
• Place the cake in the fridge for about an hour, this allows the crumb coat to harden and to securely lock in all of the crumbly bits.
• Whilst you wait for your crumb layer to harden you can start to colour the remaining buttercream. Divide the remaining buttercream evenly between 6 mixing bowls and add the desired food colouring to each bowl and mix thoroughly until the colour you want is achieved.
• Once the crumb layer has hardened, using a pallet knife you can add a thick layer of each colour in a line around the outside of your cake, applying a different colour as you work your way up to the top (see photo below). Don't worry if its looking really messy at this stage as once your cake is completely covered you will need to use your cake scraper to smooth down the sides. You can do this by pressing your cake scraper very lightly onto the side of your cake and using the turntable to guide you around until all of the excess buttercream has been removed, leaving you with a smooth and blended finish all the way around.
• Lastly you will need to smooth down the top of your cake using a pallet knife as best you can to wipe away any excess buttercream and to flatten the top.

Don't worry if the outside of your cake doesn't turn out perfectly, mine didn't as it was my first time using this technique and my first time using some of the equipment too, just remember that regardless of what the outside looks like, the inside is the real showstopper. Having said this I was extremely pleased with how my cake turned out. I love baking and want to keep gaining new skills by challenging myself to create more adventurous cakes. This was a step in the right direction for me and what I want to eventually achieve when it comes to baking. I was happy with the result as I know I'll be able to do even better next time and will be able to apply the new skills I've learnt to all of my future baking experiences. 

Thank you so much for reading! I hope your rainbow cakes turn out amazingly and that you have just as much fun making this cake as I did. Keep your eyes peeled for my next blog post as I plan on making some colourful cake pops using the cut offs from this rainbow cake.