Royal Icing:
3 cups powdered sugar
2 egg whites
1 tsp lemon juice
Directions: Whisk together egg whites and lemon juice in electric mixer. Add powdered sugar slowly until all is incorporated. Beat at high speed until thickened and holds shape. If too thick to work with, add water 1 tsp at a time. If too runny, add powdered sugar until desired consistency.
To store: put in sealed container or zip lock and keep in refrigerator. Bring to room temperature before using. (The zip lock also works great for squeezing on to the houses, just snip a small hole in a corner and you are good to go!)
For the gingerbread houses:
You will need 6 whole crackers per house. (I have found it actually works best to buy the cheap, generic, graham crackers because they are sturdier and don't crumble as easily when cutting.)
1) Using a sharp knife, cut a pointed end on two crackers. This needs to be the length of the short end of the cracker, where the roof is going to meet. (See picture)
2) Use Royal Icing along short ends of 4 crackers, for the roof and siding of house.
4) Use Royal Icing to decorate house with your favorite candy decorations!