1. Pre-heat oven to 180 degrees Celcius.

2. Sift flour and sugar into a bowl. Add butter or margarine and beat with an electric mixer on slow until combined.

3. Whisk eggs and milk together and slowly add to the flour and butter mix.

4. Once all combined continue beating on high for 3 minutes until mix is light and airy.

5. Add lemon and lime zest and quickly mix through.

6. Spoon mixture evenly into a 12 hole muffin tin, lined with cupcake papers.

7. Cook in pre-heated oven for 15-20 minutes or until skewer comes out clean.

8. Cool on wire rack.

9.3 While cooling melt butter or margarine in saucepan. Add lemon juice and mix. Slowly stir in icing sugar over low heat until all incorporated. Add hot water in small amounts gradually, as needed until smooth icing is formed.

10. Use a knife or spoon to ice individual cupcakes.

To serve: use the extra lemon and lime zest in the icing itself, or use as decoration on top of the cupcakes for a hit of colour.