This classic rock-hard royal icing for gingerbread houses is the perfect edible glue that dries to a finish so hard you can practically use it as mortar. It’s the glue that holds the whole holiday together — literally.
Royal icing hates humidity. Plan your project for a dry day or use a dehumidifier/fan. Let each section of the gingerbread house dry completely before adding the next piece. For the ‘glue’ that holds the house together, keep the icing thick and sturdy. For outlining and flooding, thin with a few drops of water.
Keywords: royal icing, gingerbread house, holiday baking, edible glue, cookie decorating