Preheat the oven to 350F then line a baking sheet with parchement paper and set aside.
Cream the butter, granulated sugar, and brown sugar together until light and creamy. Add in the egg, vanilla extract, and mix until smooth.
Gently mix in the flour, corn starch, baking powder, baking soda, cinnamon, & salt.
Scoop out equally sized cookie dough balls, flatten between the palm of your hand, fill with a rounded ½ tablespoon of cinnamon-sugar mixture, and gently seal the cookie dough. Place it on the baking sheet and flatten it to about 1 inch in thickness.
Bake in the preheated oven for 15-16 minutes. Let the cookies cool on the baking sheet for 30 minutes before transferring to a cooling rack to cool fully.
Top each cookie with the butterscotch syrup, some crushed-up pecans, a sprinkle of the leftover cinnamon sugar, and enjoy!