Flooding: For icing to flood your cookies (i.e., to create a smooth, flat layer of icing across the surface), add water, 1 tsp. at a time, until the desired consistency is reached.

The key to making these edible works of art is royal icing, the glossy mix of meringue powder, powdered sugar, and water, that stays just liquid enough to paint, marble, and pipe, and then dries hard.

Both rely entirely on royal icing, a multiuse mixture of confectioners' sugar and egg whites, plus an acid stabilizer that is firm upon piping and dries very hard. Our confectioners' sugar in the ...

"Royal icing contains egg white, so it's stretchier and just easier to pipe — plus it will dry completely hard over night. Water icing won't." Kim-Joy says of your icing options.

Pipe white royal icing onto the rooftops to look like snow. If desired, decorate the sky with small white dots to look like falling snow (alternatively use white sprinkles).