Please read the details in the post before you start to make this icing, there's details on how to dry it, troubleshooting guides and more about cookie decorating,
Add in the powdered sugar and mix together slowly until all the liquid and powdered sugar is combined. If using flavored extract such as vanilla (it must be oil free!) you can add it now, I don't typically add flavor to my icing as I prefer to add it to the cookies.
Your icing should have semi-stiff peaks (see photos in post) when the icing is ready, not floppy peaks!
This icing will need to be thinned out prior to decorating cookies with it, please scroll back up to read the paragraph in the post for specific details on how to do that.
found on www.noshtastic.com