Royal Icing for Gingerbread Houses

1. Put the meringue powder in the bowl of an electric mixer; add the warm water and hand whisk for approximately 30 seconds, until all the lumps are gone.
2. Add the cream of tartar and hand whisk for approximately 30 more seconds, until all the lumps are gone.
3. Pour all the icing sugar into the mixer bowl with the meringue powder and cream of tartar combination, place the bowl on your mixer stand and, using the paddle attachment, mix on low speed for 10 minutes. Your icing will be thick and perfect for making gingerbread house walls stay together.