Preheat oven to 350ºF. Line baking sheets with parchment paper.
To the bowl of a stand mixer with a paddle attachment, add cold butter, granulated sugar, and brown sugar. Beat on medium speed until light and creamy, about 2-3 minutes.
With the mixer on low speed, add eggs, one at a time. After fully incorporated, add the vanilla, stopping to scrape the bowl as needed.
In a medium bowl, whisk together flour, baking soda, and salt.
With the mixer off, add the dry ingredients to the butter mixture. Mix on low speed until just combined.
Mix in 1 cup pecans, reserving the rest for the topping.
Using a 2-tablespoon scoop, drop dough onto the lined baking sheets, spacing them about 2 inches apart. Add a few pecan pieces to the top of each cookie.
Bake for 10-12 minutes, or until cookies are set. They will be puffy and not appear wet.