1/2 cup butter, softened
2/3 c. sugar
1 egg yolk
1 T. grated lemon zest
1 tsp vanilla
1/2 cup flour
1/2 cup plus 2 T cake flour
1/2 tsp salt

Glaze:
3/4 cup powdered sugar
1 T. plus 1 tsp fresh lemon juice
1 tsp grated lemon zest

Cream together butter and sugar until light.  Beat in egg yolk, zest and vanilla.  In another bowl, combine flours and salt.  Add to butter mixture and remove from bowl and press into a ball. 

Divide the ball into two pieces, handling lightly on a floured board or wax paper,  form each piece into a small log about 1 1/2 x 4 inches.  Wrap in plastic or wax paper and chill (up to 1 week).

Preheat oven to 375 degrees.  Lightly grease cookie sheets.  Cut each log into 3/8 inch slices.  Arrange slice on cookie sheet on inch apart.  Bake about 10 min until edges are golden and centers are set.  Let cool and ice.

For glaze:  Mix powdered sugar, lemon juice and zest together.  Spread on cooled cookie and allow to dry thoroughly before storing between sheets of wax paper.

Would recommend doubling the recipe since these do not last long!