Preheat oven to 350 degrees. Line a 9x13 inch baking pan with two strips of parchment, leaving an overhang.
Add the flour, baking powder, and salt to a medium bowl. Whisk quickly to combine and set aside.
Place the butter in a medium saucepan. Allow the butter to melt and cook, over medium heat until the butter turns a nice golden brown and smells deliciously nutty. Remove the butter from heat and strain into a small bowl to remove the dark bits. Set aside to cool.
In a bowl of an electric mixer fitted with a paddle attachment, over medium/high speed, mix the brown butter, brown sugar, and granulated sugar until combined. Add eggs one at a time, mixing well with each addition. Mix until the mixture is light and fluffy, about 3 minutes. Add vanilla, and beat to combine. Reduce the speed to low. Add flour mixture all at once and mix until just combined. Remove bowl from mixer. Fold in the walnuts and chocolate. Mix until combined, pour into prepared pan, and even out with an offset spatula.
Place pan in the oven and bake for 30-35 minutes (do not overbake). Remove pan from oven and allow to cool completely. Using the overhang, lift the parchment paper and transfer blondies to a cutting board. Cut into 1-2 inch squares, or if you’d like to rock some shapes, use a 1 ½ - 2 inch cookie cutter.
Makes a bunch of blondies. I forgot how many, maybe 20. Fight me.