Last updated on Feb 3rd, 2021 at 02:02 pm

*This recipe makes 24 pie halves and 12 pies.


  • 125g unsalted butter, softened
  • 200g caster sugar
  • 1 large egg, beaten
  • 350g plain flour
  • 1 tsp bicarbonate of soda
  • ½ tsp salt
  • 225ml buttermilk
  • 1-2 Tbsp hot water
  • 6 food colours: red, orange, yellow, green, blue, violet


  1. Preheat your oven to 180ºC and lightly grease two whoopie pie tins or line two large baking sheets with greaseproof paper.
  2. In a mixing bowl, cream the butter and sugar together until light and fluffy, then add the beaten egg and stir together.
  3. Sift the flour, bicarbonate of soda and salt into the bowl a little at a time and fold into the mixture after each addition.
  4. Pour in the buttermilk and whisk to make a smooth batter. Add a tablespoon or two of hot water (not boiling) if you need to loosen up the mixture a little.
  5. Divide the whoopie pie mixture evenly between six bowls and colour the batter. Colour the contents of one bowl in red, one in orange, one in yellow, one in green, one in blue and one in violet.
  6. Stir the contents of each bowl well so that the colour is consistent throughout the batter.
  7. Using a tablespoon measure, scoop up a generous mound of coloured batter and transfer it to the pie tin or baking tray. If using a tray, the batter should spread to be around 5cm wide. Repeat to make 24 pies halves in total.
  8. Bake for 10 to 15 minutes. Let the whoopie pies cool slightly before transferring them to a wire rack. Use a palette knife to help you transfer them.
  9. Allow to cool completely before icing the centres.

If you don’t have all six food colours, make your own by mixing blue and yellow to create green; red and yellow to create orange; and red and blue to create violet. Build up colour gradually until you have colours you are happy with.

Filling the pies

You’ll need:

  • 450g buttercream to fill the whoopie pies
  • Your star Nozzle
  • Piping Bag


  1. Arrange your whoopie pies in pairs according to colour and have them close by. Make sure the pies aren’t touching each other, as their colours can rub off on each other.
  2. Place your star icing nozzle inside a piping bag and set them to one side.
  3. Make your buttercream, then half-fill the piping bag with it, twisting the end of the bag tightly to prevent the buttercream from squeezing out at the top.
  4. Carefully lift a whoopie pie half, cupping it in the palm of your hand. Press the nozzle to the centre of the pie and squeeze gently on the piping bag to press the icing out. When it comes out, slowly move the bag around in a circle as you pipe.
  5. Pipe a spiral all the way around the pie until you’ve come full circle. At the end of the circle, move the star nozzle back to the centre of the pie, stop squeezing and lift it away. Don’t worry if it looks messy in the centre – it won’t be seen.
  6. Lightly sandwich the second half of the whoopie pie on top of the icing. Don’t press down or you’ll ruin the effect of your icing.
  7. Repeat the steps above with the other pie halves and leave the buttercream to firm up for 10 minutes before serving.

Have fun experimenting with different icing nozzles to see what effects you can create with your buttercream. Instead of using the open star nozzle to pipe a large swirl inside the pie, pipe small individual swirls – or try decorating with a ruffle or basket weave nozzle instead.


This recipe was taken from Issue 4 of Cake Decorating Series.

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