Preheat your oven to 300°F (149°C) and toast the chopped pecans on a lined baking sheet for 15 minutes, stirring twice. Turn the oven off and set the pecans aside.

In a large bowl, beat the butter on medium speed for 1 minute until smooth and creamy. Add in the granulated sugar and brown sugar, and beat on medium high until fluffy. Mix in eggs and vanilla on high speed, scraping down as needed.

In a separate bowl, whisk together flour, cornstarch, baking soda, and salt. Gradually mix into the wet ingredients at low speed until combined. Add the toasted pecans and mix on low for about 5-10 seconds until evenly distributed. Cover the dough and chill for at least 3 hours.

Remove the dough from the refrigerator and let it sit at room temperature for 20-30 minutes.

Preheat the oven to 350°F (177°C) and line two large baking sheets with parchment paper. Scoop and roll dough into balls, about 1 tablespoon each, optionally rolling in granulated sugar.

Bake the cookies for 11-12 minutes (or 13 minutes for crispier cookies) until slightly golden brown. Allow cooling on the cookie sheet for 5 minutes before transferring to a cooling rack.