Stiff Royal Icing
Gingerbread house icing you can eat. It holds together really well! 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 tablespoons 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.