Preheat the oven to 350°F. Spread the chopped pecans in a single layer on a baking sheet. Toast for 6-8 minutes then set aside to cool completely.
On the stove top in a heavy bottomed pot simmer the butter over medium for 6-8 minutes or until light amber in color. Pour into a mixing bowl and chill for 1 hour or until the butter begins to solidify.
Using a hand mixer beat the browned butter until creamy. Add the powdered sugar and brown sugar gradually with the vanilla extract until creamy.
Add the flour 1 cup at a time beating just until combined. The dough will be stiff.
By hand mix in the toasted pecans. Divide in half and and roll into 2 logs. Wrap in plastic wrap and chill for several hours until firm or overnight.
To bake preheat the oven to 350°F and line a baking sheet with parchment paper.
Slice the logs into 10 equal slices. As the dough softens gently press any crumbles together and shape into rounds, if needed. Place at least 1-inch apart on the baking sheet.
Bake for 18-20 minutes until golden brown. Cool on a cooling rack.
Store tightly covered at room temperature.