Mix all ingredients on low until fully incorporated.
Scrape down sides of the bowl and increase speed, mix for at least 6 to 8 minutes until fluffy and shiny.
Cover with a damp towel until ready to use.
Place in piping bag or use spatula to spread onto the gingerbread house pieces to stick them together.
This icing can also be used to decorate the tops of cookies.
I usually will reserve the 2 tbsp of warm water until the end, to use to get the desired consistency. If the icing is too runny, add more powdered sugar. If the icing is too stiff, add more water in very small amounts.