Preheat oven to 350 degrees F.
In a large bowl, beat butter until creamy looking. Add powdered sugar; mix until light and fluffy. Add lemon zest and vanilla extract; beat well. Add flour and cornstarch into butter mixture and mix well until well combined. NOTE: At first the dough will look dry - but don't worry, as the dough slowly comes together as you mix it and the butter melts into the dry ingredients.
Do not refrigerate this dough, as the butter will harden and make the dough unmanageable for rolling to a ball.
Using your hands, roll cookie dough into 1-inch balls. Place onto ungreased cookie sheets and bake 15 minutes or until bottoms are light brown. Remove from oven, carefully remove from baking sheet, and cool on wire cooling racks (when warm the cookies are delicate).
When cookies have cooled, spread Lemon Frosting onto top of cookies.
Yields 6 dozen cookies.
In a medium bowl, combine butter, lemon zest, lemon juice, and powdered sugar; stir until well mixed. Additional lemon juice may be needed to get the frosting thin enough.
After making many batches of Lemon Frosting, I now thin the frosting with additional lemon juice or water and dip the top of the cookie into it. This technique is much faster and easier.
* Very important - please read! You must use room temperature butter (not softened or melted butter). I get emails from bakers saying that their cookies turn out all crumbly. It usually turns out that they have not used room temperature butter. I, personally, make these cookie every year for our Spring Teas. The recipe is correct. These cookies are always the favorite at our teas.
NOTE: If you live in a high humidity area, check out comments below. See below for butter softening tricks if you absolutely do not have time to bring your butter to room temperature by letting it sit out on the counter for at least 1 hour to overnight.
** Yes, this is correct - use 1 1/2 cups cornstarch.
High Tea Lemon Cookies Recipe: https://whatscookingamerica.net/Cookie/HighTeaCookies.htm