Cakery Bakery: the Whisk Kid’s Rainbow Cake

If there’s one thing I’ve learned when it comes to baking, it’s that you should never bake something for the first time if it absolutely has to go right. Well, you can, if you want. And if you’re an instinctive, super-confident baker you could probably do it and have it go marvellously. Not me, though. I need to do some reconnaissance. When I fly by the seat of my pants, I inevitably burn my pants.

Thus it was that I decided to spend some time this week making a rainbow cake (one of my possibilities for Henry’s birthday in a couple of weeks). I wanted to see whether it really would look as good as it did on TV, or whether that was just a bit of Martha magic. And it’s by far the most complicated, lengthy cake I’ve ever attempted, so I didn’t want to try it for the first time while also trying to hang streamers.

I used the recipe here for the cake. It’s a simple enough sponge – though it only includes egg whites, rather than the whole egg – to the extent that you could probably substitute a packet mix if you were sure of your quantities.

First, find some identical cake tins. It really helps if you have as many of the same size as possible, but they have to be identical. I had two (argh). Grease the whole tin very thoroughly and line the bottom with baking paper. If you find this task as hideously annoying as I do, here’s the best way I’ve found to do it: cut a square of roughly the right size, and press it into the bottom of the greased tin. Score around the edges with your fingernail, and take out the paper. You should still be able to see where you scored, and cut it to exactly the right shape.

As far as the cake mix goes, you combine dry ingredients in a smaller bowl, then cream butter and sugar in the largest bowl you’ve got. Weigh your large bowl before you put anything in it. I’ll explain later, honest. The recipe asks for a freestanding mixer with paddle attachment (of course it does), but in the absence of this swanky equipment I just used my handheld electric mixer. It worked fine. Once the butter and sugar are combined, add the egg whites in slowly, mixing all the time, then the dry ingredients and milk. Your arm will really be aching by this point, but keep on – everyone loves an over-developed bicep.

Then comes the fun part. Divide the mixure into six equal parts. The easiest way to do this is to weigh it out (that’s why you weighed your bowl earlier, so you can subtract it from the total weight with the mixture). Put each mix into a separate bowl, and add food colouring to each one.

Now, a note on food colouring (I told you this was an odyssey). The only colouring you can get in any decent-sized UK supermarket is the liquid stuff in bottles. Since this was just a test, I got it, but it wasn’t ideal. It’s much paler than the gel or paste, and seriously liquifies your cake mix. For proper, bright cake colours, you need something like this, which you can find in specialist cooking shops or online. I’ll pick some up if I end up doing this for Henry. You can never go wrong with food colouring in the house.

Where are we now? Right, cake baking. Each one goes in for about 10-15 minutes (depending on how watery the food colouring made your cake mix). If you’ve only got two tins, like me, you have to wait until each one has cooled, hammer it out of the tin, cut more baking paper, get out more grease, and do the whole thing over again. It took f o r e v e r. We even broke for lunch. But eventually, all six layers were done, and I could get out my cake stand. Woo!

Now for the icing. Martha recommends buttercream icing, but I hate icing. Cream cheese frosting, on the other hand, is a whole other kettle of obesity. I followed my sister-in-law, who’s done something similar, and adapted this recipe by substituting some of the cream cheese with butter. The quantities in the Not So Humble recipe should give you enough to ice between the layers and then all around the cake.

I was also supposed to slice the top off each cake layer before putting it down. But I’m a big chickeny chicken, and have never dared do this yet. So I had a little mushroom-shaped cake instead of one with a flat top. Since by this point I had forgotten my own name and what the sky looked like, I didn’t mind.

In the end, I only used five of my six layers. Partly because I ran out of icing, and partly because the mossy green looked the most unpleasant. I spread frosting between each layer, then spread a very thin layer all over the cake, to stop crumbs getting caught in the icing on top. Following instructions, I put it in the fridge to set for thirty minutes, along with the rest of my icing.

[Break for exhausted slump on sofa.]

Finally! The last layer of icing, some brightly coloured chocolate beads, and some fridge time. When it comes to icing, my personal motto is ‘If In Doubt, Cover With Something Glittery’. I used a plastic spatula for the first layering and then a metal knife to go over it, but it still wasn’t terribly swanky. Until the chocolate beads! You see what happened there?!

Cutting into it was the most exciting thing ever. The food colouring is definitely not quite right: the red is orange, and the blue is smurf-coloured, for some reason known only to Dr Oetker. But the sponge is soft and damp, and the cream cheese is to die for.

The verdict, then:

Deliciousness: Yummmm. Be warned: with a cake this tall, it’s impossible to cut small slices. I’ve only had one, and I feel a bit sick. In the best tradition of birthday cakes, of course.

Complexity: This was a long, long job. The frosting went surprisingly well and I didn’t have any cake disasters, but ohhh, my aching self once it was all done. I loved it, though. Martha, you little baking wizard, you.

Washing-up pile: I honestly haven’t dared count. I used all my mixing bowls, two cake tins, six colouring bowls, both electric whisks and almost every utensil in the house. Is this the point to confess that Timothy usually does my baking washing-up, and he’s not here? Ug. (He also does almost all of the eating, so I think it’s a fair trade.)

Casualties: my Wednesday. Which will never be seen again.

8 thoughts on “Cakery Bakery: the Whisk Kid’s Rainbow Cake

  1. I approve entirely. Sorry to hear it was such an involved process, though! Also: can I just say how glad I am that I’m not the only one in this family who doesn’t like icing?

  2. ooo that looks yum! If you are going to bake it again, I would suggest buying gel food colouring, you can buy it online or from speciality baking stores. The colour is much more concentrated, and you can even use it in icing (because it is not runny like liquid food colouring, it shouldn’t affect the texture). I have made rainbow cupcakes before, and the gel colouring I used made a massive difference! The colours were super vibrant 🙂

    • Thanks, Lecinda – that’s exactly what I need! I’ll pick some up for next time. I think it’ll make a big difference – the mouldy-orange look wasn’t exactly what I was going for…

  3. Is there still a Morrisons in Whitley? I know it’s sort of other side of the town from you, but they sell the gel food colouring. The cake looks yum though, cream cheese frosting is my complete downfall.

  4. Big Asda stores have also started selling gel colouring too so it is getting a bit more mainstream and easier to get your hands on! Yours turned out great, I love rainbow cakes! Also, don’t be scared about evening out the layers! think off it as a loaf of bread and just make sure you use a very large sharp can’t go wrong! Failing that you can buy cake levellers at places like Hobbycraft which are like mini saws that do the job for you rather efficiently! and less scarily! haha

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