This rainbow cake may look complicated and elaborate but it's surprisingly easy to make, honest. And it really is worth the time and effort because look what you get at the end of it - truly beautiful to behold and a tastebud sensation!
The first thing you're going to do is preheat your oven to 350º f/180ºc. And you don't need six individual tins. I lined three 7-inch pans with parchment paper and baked the sponges in two batches. Simples! Basically, use whatever pans you have at your disposal, between 6 and 8 inches will be fine.
As for the sponges I used this recipe from Food Network:
6 egg whites, at room temperature
1 cup/225g/8oz castor sugar (divided in half)
1 cup/225g/8oz unsalted butter, at room temperature
3 tablespoons applesauce
2 teaspoons vanilla extract (don't forget to use the good stuff like Nielsen-Massey!)
2 whole eggs
2 1/4 cups/281g/10oz cake flour (sponge flour in the UK)
2 teaspoons baking powder
Start by beating your egg whites with an electric mixer or stand mixer. Beat on medium-high until eggs become foamy. It should only take a couple of minutes. Now increase the speed to high and continue beating until soft peaks form. Add 1/2 cup/112g/4oz of the sugar bit by bit and continue to beat until you see stiff peaks.
Grab another mixing bowl and cream the butter and the remaining 1/2 cup/112g/4oz of sugar on medium speed until it's light and fluffy. Five minutes should do the trick. Add the applesauce, vanilla, and eggs and mix on medium speed for another minute.
Sift together the flour, baking powder, and salt. Add the dry mixture to the butter mixture and mix on medium speed for 1 minute. Pour in 3/4 cup water and mix to combine. Finally, fold in the egg whites with a large spatula.
The next step is to divide the batter according to how many different coloured layers you'd like. If you want six different colours then divide the batter equally into six bowls. I chose two layers of three different colours - pink, yellow, green.
To get those vibrant, "pass me my sunglasses" colours I used Wilton food colouring gels:
Then, as I said above, I baked my sponges in two different batches. I kept a close eye on them and after 15 minutes in the oven a skewer came out clean.
While I let my sponges cool completely I got on with making the cream cheese frosting that would sandwich my layers together and smother the cake in its entirety. I ALWAYS use this recipe from the Hummingbird Bakery because it works like a tasty treat every time!
NOTE: I had to make 2.5 times the recipe in order to cover all 6 layers and the top of the cake. I did have some left over but I'd rather that than be caught with my frosting pants down!
With my sponges now completely cooled and my buttercream all light and fluffy and at the ready I began the process of stacking my layers and smothering my altitudinous cake!
Don't worry about making it overly smooth and even - a very large quantity of sprinkles hides a multitude of sins! Speaking of the sprinkles, and this is very important, you need to make sure that the frosting is cold before you even try pressing them on. Trust me on this one - I learned the hard way! So pop the cake in the fridge for at least a couple of hours and then let it rip with the sprinkles and any other embellishments that take your fancy!
You now have yourself a showstopper of a cake!
GW, over and out.