Once your cookies are at room temperature, start decorating as you wish, with whatever medium you like, such as the royal icing, or modeling chocolate, etc.
Let decorated cookies rest overnight or one whole day for best result, then start building
Pipe royal icing on cake board as glue, and with the help of a couple of bottles/jars, to help the walls and whatnot, stand straight. Allow resting time each time you attach something, so it would be strong enough to work on next wall, etc.
You can use runny consistency of royal icing as your snow, but I added desiccated coconut as well, the smell will be wonderful big time, gingery and coconuty :)
I also used vegan friend sprinkles as well as edible marker for drawing.