Preheat oven to 180°c. Butter and flour 8-inch square pan and line the bottom with parchment paper, bringing the parchment paper up along the sides of the pan (around 2 inches) so it sticks out a little bit from the sides. This will help you in easily removing blondies from the pan.
In a small saucepan, heat the butter while stirring continuously, till it turns amber in color and smells nutty. The moment this stage is reached, remove saucepan from the stove because it goes really fast from this stage to burnt stage! Let it cool for 5 minutes.
In a medium bowl, place brown sugar, granulated white sugar, egg, vanilla extract and browned butter and beat for 5 minutes on medium-low speed.
Mix flour, salt, cinnamon powder and baking powder in a small bowl. Sift these dry ingredients into the batter. Add chocolate chips and walnuts, and use a rubber spatula to gently fold the mixture just till combined. Do NOT over mix.
Pour the batter into the prepared pan and smooth using an offset spatula. Top with extra walnuts and chocolate chips if desired.
Place the pan into the oven and bake for 25-30 minutes. Check doneness by inserting a toothpick in the center, it should come out clean (or with tiny morsels of fudge!). Do not over-bake!
Remove pan from the oven and let sit for 10 minutes. Run a butter knife along the sides of the pan to loosen the blondies. Remove blondies from the pan by pulling the parchment paper up. Let cool for 2 hours at least.
Cut the blondies using a very sharp knife. Dip in hot water and dry with paper towel before cutting to get neat pieces. ENJOY!