Heat butter in a saucepan over medium heat until browned. It will take take about five minutes; just make sure you stir occassionally and avoid burning.
Pour butter, including the brown bits, into bowl. Let cool.
Heat oven to 350 degrees.
In mixing bowl, whisk together flour, cornstarch, baking powder, baking soda and salt; set aside. Add cooled butter, 1/2 cup granulated sugar and light-brown sugar to Kitchen Aid (or similar) with paddle attachment and mix for a few seconds.
Add egg, egg yolk and vanilla and mix until combined. Slowly add in flour mixture and continue to mix.
In shallow dish, mix together cinnamon and 1/4 cup sugar; set aside.
Roll about a teaspoonful of dough into balls, then roll in cinnamon and sugar mixture. Place
onto parchment-lined baking sheet (about 2 inches apart).
With bottom of a flat glass, gently flatten each ball to about 1/2 inch. Bake for about 8 minutes.
Enjoy!
Makes about 2 dozen cookies.