For the cinnamon sugar topping, whisk cinnamon and sugar together in a small bowl and set aside until ready to use.
Combine flour, baking powder, cornstarch, salt, and cinnamon in a medium bowl until well mixed.
In the bowl of your stand mixer (or a large bowl with a hand mixer) beat butter and sugar for a full three minutes, until the butter is pale and fluffy. Beat in eggs, one at a time, until fully incorporated, then beat in vanilla.
On the slowest speed of your mixer, add flour mixture to butter mixture until a smooth cookie dough forms. Refrigerate dough for at least 30 minutes (60 if you have the time). While the dough is chilling, scoop out rounded teaspoons of cookie butter onto a small cookie sheet lined with wax paper. Place in freezer for about 15 minutes.
Preheat oven to 350 degrees and line two cookie sheets with parchment paper. Remove dough from the fridge and the cookie butter from the freezer. Scoop one tablespoon of dough and place in the palm of your hand, then use your thumb to make an imprint in the center of the dough. Place one cookie-butter dollop in the center, and cover with another tablespoon of dough. Roll to cover the seams and then drop into the cinnamon sugar mixture to cover.
Place at least 2 inches apart on the cookie sheets, and bake for 12-14 minutes at 350 degrees or until the edges of the cookies are just set. Let cool for a few minutes before carefully removing to a wire rack to cool completely.