In medium saucepan over medium heat, melt butter and cook until foaming and golden brown. Remove from heat and transfer to heatproof bowl. Place in refrigerator until solidified, about 45 minutes.
In medium bowl, whisk flour, baking powder, baking soda and salt. Set aside.
Once butter has solidified, remove from refrigerator. In bowl of electric stand mixer, using paddle attachment, beat butter and sugar at medium speed 2-3 minutes until light and fluffy. Add eggs, one at a time, and vanilla. Mix until combined. Scrape sides of bowl as needed. Reduce speed, add flour mixture and beat to combine. Add pecans and chocolate chips; mix at low speed until combined. Place dough in refrigerator and rest 30 minutes.
Preheat oven to 350 F and line baking sheets with parchment paper.
Using 2-ounce ice cream scoop, portion out dough on prepared baking sheets, spacing about 3 inches apart. Gently flatten dough balls using palm.
Bake 13-15 minutes, or until golden brown. Allow cookies to cool on baking sheets 10 minutes then transfer to wire rack. Serve warm.