In a saucepan, melt the butter and gently brown it. Turn the stove to medium heat and swirl the butter in the pan for 5-7 minutes. When the butter turns a brown tint, the butter is done. Cool completely.
Preheat the oven to 400 degrees. Place the pecans on a baking sheet and bake for 5 minutes. When you can smell the pecans, they are done. Do not overbrown them as they burn easily. When the pecans are cool enough to handle, chop them into small pieces.
Lower the oven to 350 degrees.
In the bowl of a stand mixer, add the cooled butter and the sugars. Turn the mixer on and mix for 1 minute.
Add the eggs, egg yolk, and vanilla to the mixer and mix again.
In a separate bowl, mix together the flour, baking powder, and salt.
Slowly add the flour to the stand mixer and mix until well combined.
Add the chopped pecans and mix again.
With a cookie scoop, scoop the dough onto a parchment lined cookie sheet. Leave at least an inch of space between each cookie. Bake for 10 minutes or until the edges are just slightly browned. Cool on a cooling rack.