Icing directions
To make the icing, beat the butter in a large bowl until it's soft. Then add half the icing sugar and continue beating until smooth. At that point, add the remaining icing sugar with one tablespoon of the milk. Beat until creamy then add the food colouring and mix well. Don't forget, you can add extra icing sugar to thicken the mixture, or make it less stiff with a little extra milk if necessary.
Microwave directions
Heat the butter and marshmallows in a microwave-safe bowl on HIGH for 3 minutes. After 2 minutes, stir the mixture until it's smooth. Then simply follow steps 2-4. Microwave cooking times may vary.