Rainbow Cake

This cake is easy to make but looks really impressive and colourful. The kids will love getting involved!

8 slices

Easy 40 Minutes

Bright, bold and utterly delicious, our rainbow cake recipe is destined to become your go-to bake for every future birthday party! This simple yet super effective cake design is made up of a light vanilla sponge cake topped off with a generous helping of rich buttercream and decorated with Smarties in a range of vibrant shades. You can create the iconic shape of a real-life rainbow simply by cutting your cake in half, placing the pieces on their sides and sandwiching them together with icing! Get the kids involved with this easy recipe by asking them to stir the cake mix, spoon on the buttercream or position the Smarties in an arch. To create the effect of fluffy clouds, why not blob more buttercream at the ends of the cake using a piping bag!



For the recipe  Rainbow Cake

For the Vanilla Sponge:

165 g Margarine
165 g Caster Sugar
3 Medium Eggs (beaten)
5 ml Dr. Oetker Madagascan Vanilla Extract (1 tsp)
170 g Self-Raising Flour

To Decorate:

400 g Dr. Oetker Vanilla Buttercream Style Icing (1 tub)
118 g Smarties




For the Vanilla Sponge

Pre-heat the oven the 180°C/160°C/Gas mark 4. Grease and line a 8” round cake tin. Place the margarine and sugar into a large bowl and cream together until light and fluffy. 


Add the eggs and Vanilla Extract and beat together to form a smooth mixture – if the mixture begins to curdle add a spoonful of flour. Sift the flour on top and fold into the mixture until just combined.


Pour the mixture into the prepared cake tin and smooth the top. Bake in the oven for 30 – 35 minutes until lightly golden and when a skewer is inserted into the centre of cake it comes out clean. Leave the cake to cool in the tin for 15 minutes, then remove, and place on a cooling rack to cool completely. 


To Decorate

Once the cake has completely cooled, cut in half to create the rainbow shape. Spread a layer of buttercream onto one half of the sponge and then sandwich together with the other sponge.


Stand the cake on our cake board or serving plate so the cake looks like a rainbow. Cover the top and sides of the rainbow in a thin layer of buttercream.


Stick the smarties onto the front of the cake in a rainbow pattern.


With the remaining buttercream place in a piping bag a cut off the end to create a 1 cm hole. Pipe blobs of buttercream around the base of the rainbow to resemble clouds. 


Your rainbow cake is now ready to enjoy! 

To make a chocolate sponge, simply use 150g Self raising flour and 20g Dr. Oetker Cocoa Powder. 

Lay the smarties out onto the cake before you add the buttercream to ensure you have enough of each colour, if you do not have enough smarties, you can make a smaller smartie rainbow, start decorating further into the centre of the cake.

Nutritional Information for the recipe Rainbow Cake

Per Serving Per 100 g / ml
Energy 2428 kJ
580 kcal
1641 kJ
392 kcal
Fat 27.43 g 18.54 g
Carbohydrate 78.19 g 52.83 g
Protein 5.55 g 3.75 g
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