This isn’t what you’d call refined, but it was intended to bring a bit of innocent happiness to a group of people working somewhere not quite as colourful. They seemed slightly happier than usual.
The train of thought that led to this cake was: I’m leaving a work team that all worked together on a project called ‘Spectrum’ or ‘ROYGBIV’, or ‘an arch of colors formed in the sky in certain circumstances, caused by the refraction and dispersion of the sun’s light by rain’ or something like that. Perhaps it would cheer the other peons up if they had a brightly-coloured cake.
Quick version: if you want to do something similar, you should find a good basic cake recipe for your size of baking tin. Weigh the bowl that will hold the finished batter – probably the one you start with your butter and sugar in. Make it up until the point where otherwise you would be be pouring in to the tin, and now weigh the bowl again. So now you have the weight of the finished batter, which you can divide by however many colours you have. In my case this was six so I divided the weight of the batter by six and divided into six equal amounts and added the colours to six smaller bowls. You’d then pour them into the tin in the order you want them to appear. Easy, eh? Now get someone else to do the washing up.
Much more detail follows…
The recipe I used was this. I’d like you to learn from my mistakes, but I’m not completely sure which one you should be learning from.
I did two things different to this set of instructions: I multiplied the ingredients by 1.4 to allow me to use a 24cm tin, and I set the oven temperature to 180C and baked for an hour or so rather than 150C for an hour and a half. Not sure which of these caused the middle to be underbaked – you can see in the picture above that the purple bit is soggy. It might actually have been a combination of two things that caused the middle sogginess – at the end of the recipe it suggests pouring over a syrup. Well, possibly because I had the oven too hot, the centre cracked, which meant that all of the syrup soaked into those cracks, which I think caused the sodden centre.
About the rainbowosity of the cake:
There are approximately a gbillion rainbow cakes on the internet, here are three:
I rejected the Good Food approach of separately baking a layer of each colour and then sandwiching together with buttercream because, well, it looks like a bit of a faff, doesn’t it? If I have sandwich pans I’ve no idea where they are. I liked Omnomicon’s layered approach more than Katrina’s random spoon-by-spoon thing. Both these last two used box mixes, I didn’t. Now that I think about it, this is bonkers: there’s no point being all snobby about box mixes vs making from scratch if you’re about to put this much food colouring in it so you have my full permission to do whatever will make you happier.
Food colouring: You need a proper paste or gel colour – I used Wilton, which in the UK you can get from Lakeland. One person in the office (I don’t know him) walked past saying ‘that looks like a really unhealthy cake’. I get the point, but then I hope he never eats Skittles. I think one piece of heavily coloured cake very occasionally will not kill you. Whether your self-image allows you to eat rainbowy cake without sharing it with a six-year old is another matter.