2 tablespoons meringue powder (available in the baking aisle)
6 tablespoons water
Assorted food coloring
Sift the confectioners' sugar and meringue powder into a large bowl. Add the water and beat with a mixer on medium-high speed until soft glossy peaks form. Divide among bowls and tint with food coloring, if desired.
Transfer the icing to resealable plastic bags; snip off the corners. Pipe on the cookies.