Rainbow Layer Cake

RECIPE: Rainbow Layer Cake
Based on Betty Crocker's rainbow layer cake recipe)

Strong/ Deep colours that you will get from using GEL food colouring.
Liquid/ powder colouring will give a lighter shade.

         Hey guys! This week was my friend's 20th birthday, so me and another friend decided to pair up and bake this delicious rainbow cake, because rainbow cakes are awesome.
        This cake might look hard at first, but it's actually extremely easy but it just takes a lot of patience and time. To spice things up a little, we decided to make it "League of Legends" theme ish, with a Teemo- related fondant figurines on top of the cake and of course the "Happy 20th Birthday" generic sign.

Although it takes a long time to make this cake, it looks awesome and is DEFINITELY worth trying out!



  • 2 boxes Betty Crocker® SuperMoist® vanilla cake mix (AVAILABLE @ WOOLIES)
  • 2 cups water
  • 1 cup vegetable oil
  • 6 eggs
  • Food Colouring (Gel colouring preferred): 6 colours of rainbow: R O Y G B P.
    (gel colouring works a LOT better than liquid food colouring, stronger colours and no bitter taste)
Note: You can find tubes of gel food colouring in the larger SPOTLIGHT stores across Sydney + individual bakery good stores. Bakery Sugarcraft is a great bakery store: order online or visit them at Wetherill Park.

  •  2 x tubs Betty Crocker's creamy deluxe Vanilla frosting. (AVAILABLE @ WOOLIES)

Here are a few of the major ingredients for the cake: Supermoist vanilla mix + frosting + food colouring (I used a mix of powder + liquid) + cake decorating items


1.) Preheat oven to 180 degrees Celcius. Brush oil thoroughly over the insides of 3 cake pans.

2.) In a very large bowl, beat cake mix, water, oil and eggs with electric mixer on low speed for 30 seconds, then on medium for 2 minutes, scraping the bowl occasionally.

We all know how pre- batter looks. Easy step, just chuck everything in and blend.

3.) Divide batter evenly into 6 small bowls.


Another easy step. Make sure you break clumps of flour that you find with a spoon.

4.) Okay, here is where it gets only slightly tricky. Using food colours, add a TINY bit of gel colouring paste into each bowl. You don't need much as gel colouring is strong.
(1 red, 1 orange, 1 yellow, 1 green, 1 blue, 1 purple)

Here are my 6 colours. As you can see, the colours are a bit pale because powder/ liquid colouring doesn't produce the deep colours that GEL colouring paste does.

        As you guys can see, my colours aren't too strong because I used a mix of LIQUID & POWDER food colouring, thus the specks in the colours. Also, I didn't have PURPLE food dye unfortunately, so I mixed the RED + BLUE colouring together. Genius right?!  

5.) Refrigerate 3 colours of batter until they are ready to bake. Pour the remaining 3 colours into the oiled cake pans, then bake for 15- 20 minutes or when you poke a skewer/ chopstick into the middle and no batter sticks to it.

Cool the 3 cakes on a cooling rack. Wash the cake pans then bake & cool the remaining 3 cakes.

5 cake colours. Couldn't fit the last one in the photo ):
Note: If you guys don't have that many baking pans, like me, you will have to bake them ONE/ TWO at a time like I did. It takes an extra half hour to do but still the same process!



Starting from the bottom colour (Purple), frost the top of the cake layer with Betty Crocker's vanilla frosting. You can decide how much frosting you want in between each layer, but I prefer a thin layer because the frosting is already really sweet.

Repeat with Blue (2nd last), Green (3rd), Yellow, Orange then place the Red layer on top without icing.

The layers should look like this with frosting in between each layer.

7.) (OPTIONAL STEP) If your cakes are too "puffed up", then there will be a large gap in between each layer on the outside of your cake. This means that you will have to add a TONNE of icing to fill those gaps.

Like me, what you can do is cut those edges off to make the outside surface FLAT. (Compare above picture with picture below, the cake's outer layer is trimmed)

Note: TAKE EXTREME CARE WITH THIS STEP! It is difficult to trim the edges off without screwing up the perfect circle of the cake. You can get some baking paper, cut out a perfect circle and place it on top of the cake to assist you with the cutting.

This is how the cake looks with the edges trimmed off. As you can see, the surface around the cake is FLATTER allowing the frosting to be spread evenly along the sides of the cake.

8.) Spread a 1st light coat of frosting on the edge of the cake to seal in crumbs, then spread a 2nd & final layer of thicker frosting on the cake. Smooth it out with a larger, flat knife.

Spread frosting on the Red top layer of the cake, again smoothly.

The completed frosted, rainbow cake should look like this!

9.) Now, decorate the cake with whatever the hell you want! Add hundreds and thousands on top/ to the sides, mix the food colouring with leftover icing then using a piping bag, make figures/ shapes on the top of the cake.

Be creative.

Teemo, with teemo hat and goggles! Also his mushroom traps. All made with fondant.

        I won't go into details of how I made this, but basically I used FONDANT (Click here for a cooler League cake) to shape these figurines. Then I used the remaining food colouring to colour each part of the figurine, then pieced it together to make this.

        Making figurines with fondant requires a LOT of effort and even then thats an understatement! In the future, I'll make a post about fondant when I have the time.

Anyway, here is the final cake!
I know, the writing is ugly but I blame my friend's shaky hands :D
Yep, happy 20th birthday such a generic message. Could've drawn a cool picture of a dragon or something but nope. Great effort though right?

And here are more pictures of the insides of the cake when cut!


The cake was so tastily moist, looked awesome but was so sweet! Went to the Garden Buffet at The Star so we were full before we even brought the cake out.

Next time, I should probably consider where we're eating before I bake a cake with heavy frosting.


  1. GOOD WORK :D I've made a rainbow cake before too; like a bajillion years ago. Check this recipe out, it's what I used! It's much much much quicker.

    the result:

    1. Alicia, that's an amazing looking rainbow you made there! You have fantastic colours going on there in the cake, obviously from the Betty Crocker gel colouring that you used. Too bad Sydney's major grocery chains don't stock them! Also, the light- blue buttercream frosting is really creative and looks awesome.

      Plus, I love how you are nutrition- wary as most cooks/ bakers/ bloggers whatever we call ourselves don't put in any effort to bring out such an important issue on healthy eating.

      Your other blog articles are amazing and if you ever read this reply, what camera do you use to take those photos? :)


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