Lemon & Lime Cupcakes

Pre-heat the oven to 180 Degrees Celsius and prepare a tray with cupcake cases
Firstly cream the butter and caster sugar until smooth. Then whisk in the eggs (don't panic if it looks like it curdles!) Then add the self-raising flour and baking powder. Once fully mixed, split the mixture between two bowls (about 1/3 of the total mixture into the second bowl). In the first, flavour the mixture with the lemon flavouring/extract (to your taste. Note, you can use juice but may need to use a lot for a good flavour... if so add some extra flour so the mix is not too wet). In the second bowl, add the juice of 1 lime and some green food colouring.
Once the cake mixtures are ready, place a tablespoon of the lemon flavoured mix into the cupcake cases followed by a smaller amount of lime flavoured mixture
Using a skewer or lollypop stick, lightly fold the mixtures together in the cupcake cases to create a green and yellow marble. Then place in the oven to bake. he cakes normally take ~18mins to bake however this may change with different ovens. Therefore wait until golden brown ontop and use a knife/skewer to check if done completely (will come out the middle of a cupcake clean if baked through).
Once baked, take the cupcakes out of the oven and allow to cool on a rack. Whilst the cakes are cooling, the butter icing can be made. Cream the butter and icing sugar together. Split the mixture into two; flavour one bowl with lemon, and the other colour green/flavour with some lime juice.
Once the cakes are cool, into a pipeing bag place the butter icing. A dual colour bag (as pictured) will make things easier, however if you have a single one simpley fill one side with one colour and the other side with the other (a bit trickier but do-able!) Then swirl on to the cupcakes
Once done, sprinkle a small amount of lemon sherbet on top. (I also add a little lime-flavoured chocolate on top!) Then Enjoy!