Rainbow Party - the Easy "Cheat" version of Rainbow cake

Rainbow Party – the Easy “Cheat” version of Rainbow cake

The first time I tried to do the famous Rainbow Cake started by Whisk Kid, it turned out like this:

Go ahead.

Take it in.

Has your hand left covering your mouth yet so you can scream “What the ____ happened?”

Yeah I cried. No really.

I was doing a test run of it for a family BBQ and it just imploded onto itself with my saucy homemade frosting.

I thought I could make frosting from icing sugar. Me. Oh that’s funny.

I was so mad after that waste of time that I actually whipped up a batch of rainbow cupcakes after the fact to prove that I could still actually bake something.

Ok there was hope yet.

So when it came time to do the actual “Rainbow Birthday Party” Rainbow cake, I went to what I like to call the Easy “Cheat” version of Rainbow cake that I modified from the Rainbow Cake recipe on the show Best Recipes Ever – which gave me the idea of using a colour layer of the cake made from icing vs cake batter.

I did this last year for Little L’s birthday and it worked so I figure if it ain’t broke, don’t fix it.

That way you don’t have to make 6 layers of cake and 6 layers of icing and pray it doesn’t topple over with your dowels or straws plugged in holding it in place.

You only make 4 thin layers of cake and 2 layers of icing and still get the same Rainbow effect when you cut in.

This is a one day cake recipe. You know the kind that you go “Oh no that has to be done by tomorrow” and panic sets in.

How modified is this version?

Have you met my friend Betty Crocker? We go way back. Betty makes cake mixes and icing for your busy self and can almost guarantee that your end product will be edible. Unlike your from scratch recipe that you totally thought you rocked until you bit into it.

Side note – the back of this box tells you to use 3 egg whites for this and *if* you want, you can substitute whole eggs.

Use the whole eggs.

You need a binding agent and eggs do that. If you use egg whites, your cake batter after it is baked, will be vastly more light (read: crumbly) and it won’t hold together remotely as well. I have used this box many times and have tried both ways and I always use whole eggs with it now. Especially when you’re baking cake layers that you can’t afford to have fall apart.

If you’re a foodie or a baker that cringes at any possibility of using a boxed mix of anything, stop reading now. It’s only going to get worse.

So here’s what you’ll need:

– 1 box of Betty Crock Super Moist cake mix (yes just one box)

– 4 containers (possibly 5) of Betty Crocker Whipped Vanilla frosting (which is a very white, not cream coloured frosting/icing)

– Wilton Gel Icing Colours in all 6 shades of the rainbow

– PAM or another non-stick spray

– Four 9″ baking pans

– Parchment or Wax paper

– Cake Icing Spatula

– Cake smoothing tool or bench scraper to help smooth out your icing

Before you start this, clear out room in your freezer for your cake. It’s part of the process.

Step 1

Write out your cake colour layer list. Laugh all you want, when it’s 6 hours later and you’re tired, I promise you this chart will make you very happy to have it to refer to.

Step 2

Make up cake batter mix. Measure out 1 cup of the batter and pour them into your cake baking pans. That way you have an even amount of batter in each pan. If you have a scale you can do this by weight.

Step 3

Mix up your Red, Yellow, Blue and Green cake colour batters.

Coat cake pans with Pam/cooking spray.

Pour in batter.

Step 4

Bake 2 pans in the oven at a time for HALF THE TIME it says on the box.

Normally you wouldn’t have split up that batter into 4 pans (it would have been 2) so each pan would have baked for approx 20-30 mins (the box says 25-30 mins for a 9″ pan) depending on your oven.

But because the batter is split up into 4 pans (again not 2), you don’t need to bake it as long.

For me in my oven at 350 degrees this 10 mins. Check with a skewer to make sure it’s baked through.

Step 5

Let cool and then flip over the baked cakes onto parchment or wax paper.

See how thin the cake layers are? This is a good thing. That means there is less to trim off to even it out and all the layers are now the same size.

I repeat, let them cool.

Do not touch them.

Do not go “Oh it’s been 20 minutes maybe they’re ready to be iced now.”

Walk away.

Do something else.

In fact go to Step 6.

Step 6

Get two of the icing containers and scoop out all the icing in each container into two separate bowls.

Add in your Orange and Green colouring into 2 separate bowls, one per each colour (yes I had to write that – you’d be amazed at how I read recipes sometimes).

The next step I must thank Angry Julie for. This changed the way I made my cakes and it changed the ease of icing my cakes.

Get a piece of parchment or wax paper and trace the bottom of the cake pan onto it. Flip the paper over.

Get your icing and put almost all of it in a glob in the middle of the cake pan outline. Spread it out clockwise and then counter clockwise with a spatula until it fills out the circle outline, to create a round layer of icing.

I put them both on a large round dinner plate.

Step 7

By now your cake pans should be cooled enough that you can trim off the excess rounded dome that can occur on the baked cake layers. I used a serrated bread knife.

Having your layers as flat as possible is very important.

Step 8

Take all your cake layers and your icing layers and put them in your freezer. I left mine in for several hours.

Step 9

Get your almost frozen cake layers out of the freezer to get ready for an icing crumb coat.

Initially I put down parchment paper on the cake tray and thought maybe I’d pull it out after I iced it (to avoid a messy tray) but then I thought “what could possibly go wrong with me doing that” and changed my mind.

Begin to stack your cake layers in the order of the rainbow colours, purple, blue, green – icing layers included (which should now be pretty much frozen).

If you find your icing layers are a tad bigger than the cake layers, just trim off the excess with a knife.

Step 10

Do a crumb coat (aka the first messy layer of icing/frosting of your cake). Don’t panic when you see the Orange or Green icing layers mix in with the crumbs. It’s called a crumb coat for a reason.

Put the cake back in your freezer for about another hour.

Step 11

Do a final icing/frosting coat of your cake. Please make sure your crumb coat feels stiff and relatively frozen before you do this.

DO USE for your own sake a cake icing spatula and/or a cakes smoothing tool. Don’t use a knife or your regular spatula. You will drive yourself crazy.

FYI – Glass of wine not necessary in icing but yet may make this whole process easier.

You’re done. Put your cake away in the fridge for the Birthday Party the next day.  Decorate or do not decorate the outside of it at your own choice.

Step 11

Take a deep breath and cut into the cake during the birthday party the next day.


So again, the red, yellow, blue and purple layers are cake, the orange and green layers are icing/frosting. Still a great rainbow effect!

On a food colouring note, I also made up a batch of rainbow cupcakes for a friend of my daughters who has a peanut allergy and can’t eat anything made with the Wilton Gel products (as the current ones state there may come in contact with peanuts) so I used the regular Club House Food Colouring ones for these. Of course in the chaos I forgot to take a photo of the finished cupcakes the day of the party.

But I just wanted to show you what the colours would look like if you went this route vs using the gel colours.

A lot more pastel vs the gels. I know they make a Neon version of the Club House ones but I haven’t tested those out yet.

Mind both the cupcakes and cake tasted fabulous.

Thank you Betty Crocker!

PS – If you’re visiting this post because you found it through Pinterest (as this cake post seems to have taken on a life of its own), please feel free to check out the Rainbow Birthday Party post where you can see all of the crafts and projects that I did for the party as well as links to each craft.