- 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
- Preheat the oven to 180°C/350°F/Gas Mark 4. Grease and line the base of 2 or more 18cm diameter sandwich cake tins. You’ll 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.