Wow! What birthday girl or boy wouldnít be delighted with this brightly coloured rainbow cake, imagine their surprise when they cut into it. Itís not difficult to make with our easy mix sponge cake recipe, you just have to be bold with the colours and use concentrated gel paste colours which are now widely available in major supermarkets, cake decorating shops and online. Use 18cm round sandwich cake tins, youíll probably need to bake the sponges in batches, if you donít have 5 tins, but this is not a problem as the cakes donít take long to cook. Once baked you can freeze the sponges until you are ready to assemble and decorate.
500g sunflower spread (not low-fat), at room temperature
500g caster sugar
500g self-raising flour
10 eggs, at room temperature
Gel paste food colours in blue, green, yellow, orange and pink
For the buttercream icing:
400g icing sugar
200g butter, softened
Coloured sprinkles, to decorate
This cake will keep for 3-4 days in an airtight container stored in a cool place.
Preheat the oven to 180įC/350įF/Gas Mark 4. Grease and line the base of 2 or more 18cm diameter sandwich cake tins. Youíll need to bake 5 cakes in total but the tins can be reused.
Place the sunflower spread, caster sugar, flour and eggs in a large mixing bowl and whisk together using an electric mixer until soft, smooth and creamy.
Divide the mixture equally between 5 bowls. Add a small amount of food colour to each bowl, mix to colour evenly, adding more colouring if necessary to get vibrantly coloured mixtures. Spoon a coloured mixture into each tin and spread level with the back of a spoon. Bake for 30-35 mins until well risen and just firm to the touch. Cool in the tin for 5 mins then turn out onto a wire rack to cool. If reusing the tins, wash, grease and line with clean paper before adding the next mixture.
For the buttercream, beat the butter with an electric mixer until smooth. Add the icing sugar, about one-third at a time, whisking well between each addition until smooth. You need a soft spreading consistency so if the buttercream is too stiff add 1tbsp freshly boiled water from the kettle and whisk again until light and fluffy.
To assemble, place the pink cake on a plate or board and spread with a thin layer of buttercream. Top with the orange cake then the yellow, green and blue, spreading a thin layer of buttercream between each one. Using a round bladed knife spread the remaining buttercream over the top and sides of the cake, swirling it slightly. Decorate with coloured sprinkles over the top.