500g sunflower spread or butter, 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 sugar200g butter, softenedColoured sprinkles, to decorate
18cm sandwich tins
Step 1: Cakes
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. I bought 5 inexpensive tins from the local supermarket to save a heap of time!
Tip: Weigh the empty mixing bowl, then re-weigh once all the batter is mixed. Divide the weight of the batter by 5 so you know how much to put into each bowl before colouring.
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. You could do this by eye, or by counting spoonfuls. I weighed it out so it was pretty exact.
Add a small amount of food colour to each bowl, mix to colour evenly, adding more colouring if necessary to get vibrantly coloured mixtures. I used Dr Oetker gels and had to use a whole tube for each layer giving a pastel effect. Other products may give a darker, more vibrant result.
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.
Step 2: Buttercream
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.
Step 3: Assembly
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.
I found this part the trickiest. I layered the cake with the buttercream and then refrigerated until the buttercream firmed up a bit.
I then spread the remaining buttercream around the top and sides. It is possible to do it all in one go but I found the layers were sliding about a little.
Step 4: Decoration
Decorating with sprinkles was more of a challenge then I expected, so, with the buttercream still fairly soft I threw sprinkles around the sides in the hope they would stick. This method worked but left my kitchen covered in rainbow sprinkles!
I decorated the top with small coloured sweets, more sprinkles and candles.
Then refrigerate the whole cake to help the buttercream set and the layers stay in place.