1In large bowl, low speed, beat butter until creamy. Add powder sugar; mix until light and fluffy. Add lemon zest and lemon juice; beat well. Ad flour and cornstarch into butter mixture and mix well until well combined.
2Divide dough in half and shape each half into 8" x 1" rolls. Wrap each individual roll in plastic wrap. Refrigerate until firm, approximately 1 to 2 hours.
3Using a sharp knife, cut each roll into 1/4 inch slices. Place slices onto cookie sheet, 2 inches apart.
4Bake 8-12 minutes or until bottoms are light brown, tops should not brown. Remove from oven, carefully remove from baking sheet, cool on wire rack.
5When cool, spread Lemon Frosting onto top of cookies.
In medium bowl, combine all until well mixed.