In the bowl of a stand mixer or large mixing bowl, beat egg whites on medium-low speed until frothy, about 1 minute.
With the mixer on low speed, slowly add in confectioners’ sugar and vanilla.
Once fully incorporated, increase speed to medium-high and beat until stiff and shiny peaks form.
Divide icing among small bowls and dye with gel food coloring if desired.
Transfer to piping bags and decorate cookies.
