Rainbow (White Chocolate Mud) Cake

By Fongolicious - August 12, 2012

Its been a little while since I’ve baked and built a kid’s birthday cake. My last one was December last year. Strangely enough I still get a few hits for the double rainbow unicorn cake. I guess with a name like that, google search goes a little crazy! This time, I got another request for a rainbow theme. However, I decided to have a double rainbow of a different nature. A M&Ms rainbow on the outside, but a fun little surprise on the inside!!! Yes indeed, the kiddies did go a bit wild! Not sure if it's from the sugar, the vibrant cake or the fact they’re getting cake. I think it's the latter. Whatever the reason – this cake proved very popular and was “Fongolicious” as they ate it.

On the technical side, as the title suggests, I adapted a white chocolate mud cake recipe (from Donna Hay Modern Classics book 2), divided the mixture into 6, coloured them, then in order of the spectrum, I poured the mixture into the middle of the pan. As you pour each colour in it pushes the previous colour out to the edge. There are a few sites that give you some advice on how to do this in more detail. They used packet mix sponge cake. Any sort of neutral coloured mixture will work.

White Chocolate Mud Cake
185g butter, chopped
1 cup milk
1 1/2 cups caster sugar (I used 1 cup)
150g white chocolate, chopped
2 cups plain flour, sifted
1 1/2 teaspoons baking powder
1 tspn vanilla essence
2 eggs
Yellow, red, pillar red and blue liquid food colouring

1. Preheat the oven to 150 to 160C. Grease and line, with baking paper, a round cake tin (22cm).

2. Place butter, milk and sugar in a medium saucepan over low heat and stir until the butter melted and the sugar is dissolved. Take this off the heat, add chopped chocolate while butter mixture is still hot. Stir until chocolate melts and is smooth.

3. Sift flour and baking powder in a mixing bowl. Add vanilla and eggs. Add chocolate mixture and whisk until smooth.

4. Divide mixture into 6 portions, try to be as evenly distributed as possible. With each portion, add food colouring to create different colours for each portion. I chose orange yellow, red, blue, green and purple. Use separate teaspoons to mix each portion.

5. In order of the spectrum, add each portion into the middle of the cake tin. As you pour each colour, the colours pushes out to the edge.

6. Bake for 50 to 60 minutes, or until the cooked when tested with a skewer. Cool in tin, then remove from tin and decorate.

Tip: To keep the cake moist, I’ve got into a habit of putting a baking tray of water on the bottom shelf of the oven so the steam will help avoid the cake from drying out. You can also blind bake this cake (carefully place baking paper on the top of the cake mixture before placing it in the oven).

  • Decorating this cake I used a cream cheese frosting (see my red velvet cupcake recipe) and added 2 tspn of lemon juice to give a little zing.
  • Then using M&Ms to form the rainbow.
  • And hundreds-and-thousands for the sides of the cake. I found it tricky to add the 100s and 1000s to the side of the cake, I worked out using the back of a teaspoon most effective.

  • Share:

You Might Also Like


  1. You did a fantastic job Kim!
    Thank you plenty many much!!
    The pics on here look bright and beautiful.
    I love how you show the method - very arty :)

    Your not so secret admirer, lol

  2. Rainbowlicious Miss Fongolicious! Thank you ever so much, it was PERFECT! ♥

  3. omg very cool!
    it looks awesome, and such a great idea with the pouring of the coloured batters!
    awesome one kim!

    sarah :)

  4. Wow! That's so amazing! I'm a bit scared to show my cake-baking kids, they'll want me to make it. But then, the instructions are really clear so I'll just get them to make it for MY birthday. :)
    Way cool.

  5. ...And the physics of the batter layers pushing the last layer out... WOW! Cake and physics! LOL!