Marble Rainbow Cake

This bold, bright party cake features layers of marbled vanilla cake sandwiched between salted caramel buttercream. It’s just like a rainbow cake, but so much more fun – just add candles!

Prep:
45 min + chilling
Cook:
50 min
Serves:
12

Ingredients

Cake
  1. 400g butter, softened
  2. 4 tsp Queen Madagascan Vanilla Bean Paste
  3. 2 cups caster sugar
  4. 4 cups plain flour, sifted
  5. 6 sachets Dr. Oetker Baking Powder
  6. 1 ½ cups milk
  7. 6 eggs
  8. Queen Food Colour Gel in Red, Blue, Green & Yellow
Swiss Meringue Buttercream
  1. 300g pasteurised egg white from carton
  2. 500g caster sugar
  3. 500g butter, slightly softened
  4. 3-4 tsp Queen Salted Caramel Flavour for Icing
Decorate
  1. Dr. Oetker Polka Dots
  2. Dr. Oetker Sour Strands
  3. Dr. Oetker Hundreds & Thousands

Method - Cake

  1. Step 1

    Preheat oven to 180 degrees C, grease and line 2 x 20cm round cake tins.

  2. Step 2

    Combine butter, vanilla, sugar, milk, eggs, sifted flour and Baking Powder in the bowl of a stand mixer. Mix on low until all combined, then increase to high, beating until light and well mixed.

  3. Step 3

    Divide mixture evenly into six bowls using a scale or half cup measure. Tint each bowl with the following colours: Bowl 1: four drops red. Bowl 2: two drops red gel plus two drops yellow. Bowl 3: two drops yellow. Bowl 4: three drops green. Bowl 5: four drops blue. Bowl 6: two drops red plus one drop blue.

  4. Step 4

    Add bowls 1-3 into one cake tin and use the end of a spoon to gently marble colours. Repeat in the second tin with bowls 4-6. Bake for 45-50 minutes or until an inserted skewer comes out clean. Allow to cool for 15 minutes before turning out onto a cake rack to cool completely.

Method - Swiss Meringue Buttercream

  1. Step 1

    Prepare buttercream by dicing butter into 2cm pieces, set aside. Combine egg whites and caster sugar in a large bowl and sit over a saucepan of just simmering water. Whisk continuously until mixture is hot to touch and sugar dissolves.

  2. Step 2

    Transfer mixture to a stand mixer with a whisk attachment fitted. Whisk for 5-10 minutes until a thick glossy meringue forms with stiff peaks and the mixture has cooled down.

  3. Step 3

    Switch to a paddle attachment, and on medium speed, add butter a little at a time, allowing it to incorporate fully before adding more. Add Salted Caramel Flavour to taste. Increase speed to high and beat for 5 minutes until a thick buttercream forms.

Method - Assemble

  1. Step 1

    To assemble, cut cake in half horizontally using a large bread knife. To create two even layers, make small cuts while turning the cake. Place one blue-green marble layer on a cake stand and top with a cup of buttercream. Smooth with a spatula then top with the second blue-green cake. Repeat, following with red-orange cakes.

  2. Step 2

    Add a thick and even coat of buttercream around the top and sides of the cake, then chill for 15 minutes to set slightly. Use a large French star tip to pipe a border around the top and bottom of the cake, and sprinkle Polka Dots, Hundreds & Thousands and Sour Sugar Strands. Time to party!