mint (choc chip) frosting

Ingredients
125g unsalted butter at room temperature
300g sifted icing sugar
couple of drops of peppermint extract
Couple of tbsps milk
50g dark chocolate, chopped (optional)

1. With an electric whisk, beat the butter until it is smooth and creamy.
2. Bit by bit beat in the icing sugar until it is thoroughly combined.
3. Add the peppermint essence and beat in.
4. If needed beat in a little milk to make the consistency a little smoother. 
5. Stir through the chopped dark chocolate if using. Chill the frosting for at least 20 minutes before using.