Melt butter, add sugar and eggs and mix till well blended. Add flour, cornmeal, baking powder, salt, vanilla and 1-2 drops of the YL lime vitality oil; mix well. Grate finely, 3 limes. Add 1/2 of the grated lime zest to dough and mix, chill in the refrigerator for a few hours.
Form the dough into 1″ balls then press flat onto a cookie sheet, bake at 375° for 12-15 minutes or until light brown on the edges. Turn pan half way through baking time.
You can make bar cookies if you prefer by pressing all the dough into a 13″x9″ pan.
For the frosting, squeeze the juice from the 3 limes. Combine with 1 egg white and 1 drop of YL lime vitality oil, add the remaining lime zest. Add enough powdered sugar to make a heavy glaze. Drizzle or spread the icing onto the cooled cookies and let cool completely.