In a medium saucepan, melt one stick of butter. Once fully melted, allow the butter to cook over medium heat about 3-4 minutes more, until the foam subsides and a rich golden brown color is achieved. Pour the brown butter into a separate bowl and place in the refrigerator to cool and solidify, for about an hour. While the brown butter cools, roughly chop the pecans and toast them in a large skillet in 2 tablespoons of butter, over medium-high heat, stirring constantly, until lightly browned and fragrant, about 3-5 minutes.
In a stand mixer or in a large bowl using a hand mixer, cream together the regular stick of butter, cooled brown butter, brown sugar, and granulated sugar for 2-4 minutes or until fluffy.
Gently stir in eggs and vanilla extract, then mix until well combined (about 1 minute).
In a large bowl combine the all-purpose flour, cornstarch, baking soda, and salt. Gradually add the dry ingredients to the wet ingredients in ½ cup increments (mixing after each addition until just barely combined).
Stir in the toasted pecans until combined.
Chill the dough in the refrigerator before baking, at least one hour.
Preheat the oven to 375°F.
Scoop the dough into roughly shaped balls, 2-3 heaping tablespoons at a time, onto a baking sheet.
Bake for 9-10 minutes, until golden brown.
Allow the cookies to cool slightly before moving to a cooling rack. Serve and enjoy!