Rainbow Cake

• 225g unsalted butter, softened
• 410g caster sugar
• 4 large eggs
• 400g plain flour, sifted
• 2 1/2 tsp baking powder
• 1 1/2 tsp salt
• 8 fl oz whole milk
• 2 tsp vanilla extract
• red, orange, yellow, green, blue, indigo and violet food colouring

Plus

• 1 batch of vanilla buttercream

1. Cream the softened butter with a mixer until smooth. Add the sugar and beat until pale and fluffy about 5 minutes, starting on medium and working up to high speed.
2. Add the eggs, one at a time, beating on medium speed after each addition until just incorporated.
3. Combine the flour, baking powder and salt and add to the batter in three parts, alternating with the milk and vanilla, beating well after each addition and beginning and ending with the dry.
4. Now make a rainbow! Divide your batter into 7 small bowls equally. Then, using gel colours (not liquid food dye), mix a little (use a toothpick) of each colour of the rainbow to make red, orange, yellow, green, blue, indigo, violet.
5. Spoon the different coloured batter into your cake pan and spread it evenly to edge, then continue through the rainbow. If you don’t have enough cake tins don’t worry, you will just have to bake the colours in batches.
6. Bake for 25 minutes in a 180°C oven or until a skewer inserted into the centre of the cake comes out clean.
7. Let the cakes cool in the pan for 5-10 mins, then transfer carefully to a cooling rack and allow to cool completely.
8. To decorate, stack the cakes in the colour of the rainbow – with violet on the bottom up to red at the top – and spread a thin layer of vanilla buttercream between each one. Mask your cake with the rest of the buttercream and then decorate how you please.

Photo credit: Felicity Spector