In a stand mixer or using a hand mixer, cream brown sugar and butter until smooth and creamy, on medium, 2-3 minutes
Beat in egg and vanilla extract.
On low, stir in flour, cornstarch, baking powder, and cinnamon.
Cover dough and refrigerate for 1 hour.
Remove dough from fridge.
Preheat oven to 325℉ and line cookie sheet with parchment paper
Roll dough into 1 inch balls and roll in white sugar.
Place cookies 2 inches apart on prepared cookie sheet
Bake in preheated oven for 10-12 minutes. Do not over bake. Cookies will still look wet in center
Allow cookies to cool for 10 minutes on the cookie sheet before transferring to a cooling rack to cool completely.
Store cooled cookies in an air-tight container for up to 5 days.