Funfetti whoopie pies

Method

• 1
  Preheat oven to 190C/170C fan forced. Line 2 baking trays with baking paper. Beat the butter, sugars and vanilla in a bowl until pale and creamy. Beat in egg.
• 2
  Stir in the bicarb. Use a metal spoon to fold in the flour and buttermilk, in alternating batches, until just smooth (the mixture should be a little stiff).

• 3
  Use a 3cm-diameter ice-cream scoop to place rounds of mixture on prepared trays, leaving 5cm between each for spreading. Use your finger to smooth mixture around edges. Sprinkle with hundreds and thousands.
• 4
  Bake, swapping trays halfway through cooking, for 10 minutes or until firm. Cool slightly. Transfer to a wire rack to cool completely. Repeat with remaining mixture.
• 5
  For the filling, beat butter and icing sugar in a bowl until combined. Add milk and beat to combine. Divide buttercream into 2 bowls. Add a few drops of food colouring to one bowl to make pale-pink icing. Beat to combine. Add more than a few drops of pink food colouring to the second bowl to make dark-pink icing. Beat to combine. Spread the pale-pink icing on one side of a piping bag fitted with a 1cm fluted nozzle. Spread the dark-pink icing on the other side.
• 6
  Pipe the buttercream onto half the whoopie pies. Sandwich together with the remaining whoopie pies.