Preheat oven 180°C.
Line a 12-hole cupcake pan with cupcake cases (I have used union jack ones).
Put the butter and sugar in a large mixing bowl and whisk for 2-3 mins until pale and fluffy.
Gently fold in the flour, lemon extract and just enough buttermilk to make a smooth batter that drops easily off the spoon.
Divide the batter equally between 3 bowls and mix in food colouring: 1 bowl = blue, 1 bowl = red and 1 bowl = plain. Then put each coloured batter into it’s own piping bag.
In each of the cupcake cases pipe some blue, then plain and finally red. Do not fill the cases more than 2⁄3 full, as it will rise when baked.
Bake for 20-25 mins or until a skewer inserted into the middle comes out clean. Remove from the oven and transfer the cakes to a wire rack and leave to cool completely.
Meanwhile, to make the buttercream icing, put all the ingredients in a large mixing bowl and whisk for 4-5 mins until pale and fluffy.
Split the buttercream equally between 3 bowls and colour the same as the batter.
Using a large flat piping bag with a 2F size tip in, open it and along the crease (inside) on one side spoon it the red buttercream (from tip to opening), the on the other crease spoon in the blue, and finally fill the middle with the plain buttercream.
You can now use this to pipe on the cooled cupcakes, in a circle motion from outside to the middle, whilst also moving the piping bag upwards. The final effect should produce a buttercream swirl with red and blue edges.
