In a large bowl, mix together the butter and sugar until fully combined. Mix in the eggs and vanilla.
In a separate bowl, mix together the flour, cornstarch, baking soda and salt.
Slowly mix the dry ingredients into the wet ingredients until fully combined.
Cover and refrigerate the dough for at least 2 hours.
Preheat the oven to 350°F. Line 2 baking sheets with parchment paper.
Using a medium cookie scoop, scoop the cookie dough onto the prepared baking sheet. Press a pecan on top.
Bake in the preheated oven for 10-12 minutes, or until the edges are lightly brown. Allow to cool completely on the baking sheet.