Preheat oven to 325 degrees.
Line cookie sheets with parchment paper and set aside.
In a medium mixing bowl, combine butter, cornstarch and icing sugar and whip until very light and fluffy, about 8 minutes.
Start adding in flour in small amounts and mix in well.
Once all the flour is incorporated, dump the dough onto a clean counter and knead dough like you would bread.
It will be sticky, so just put a little flour on your hands. The more you knead it the more flakey it will become.
Roll dough into balls and place on prepared cookie sheets.
Using the bottom of a clean glass, press down the cookies to flatten them. If you want to, add fork tines for decoration marks (or use a cookie press as I did with the letter S).
Cook for 8-10 minutes, watching closely to make sure only the edges are slightly brown.
Let cool on a wire rack.