Preheat the oven to 180°C, 160°C fan oven, gas mark 4.
Put the cupcake ingredients in a bowl and beat with an electric hand mixer, until light and creamy.
Split the mixture into 5 small bowls and colour each individually (red, yellow, blue, green and natural).
Put the cupcake cases into the tin. Add a teaspoon of each coloured mixture to each case, starting with natural then red, yellow, green and blue. Add each colour to the middle of the last so that they make rings of colour like a rainbow.
Bake for about 15-18 minutes until springy. Cool slightly then lift out onto a cooling rack.
For the icing, beat the buttery spread, icing sugar and vanilla with an electric beater until light and creamy. Add the milk a little at a time until smooth. Spread over the cool cupcakes and sprinkle with coloured decorations.
*All information included in this recipe has been provided by Nestlé.