Preheat oven to 350 degrees.
In a small pan on medium heat, melt the butter stirring occasionally. Cook the butter until it begins to have a nutty smell and turns an amber color. Do not overcook or it will burn easily. Remove the browned butter to a glass bowl or cup and set aside to cool.
Spread the walnuts in a single layer on a parchment lined baking sheet. Bake at 350 degrees for about 15 minutes or until they are golden brown. Transfer the nuts to a cutting board and chop lightly. Set aside.
Cut a length of parchment paper to fit a 8x8 baking dish allowing the paper to come up to the top of the pan on both sides. Cut another sheet to fit in the opposite direction also trimming at the top of the pan. Spray the parchment paper lightly with cooking spray. Set aside.
Whisk 3/4 cup flour, baking powder and salt together in a small mixing bowl. Set aside.
In another medium mixing bowl combine the browned butter and brown sugar until blended. Add the egg and mix well. Blend in the bourbon and vanilla and mix just until incorporated. Fold the dry ingredients into the butter mixture just until combined. Do not over-mix.
Add the remaining 1 tablespoon of flour to the chocolate chips and toss until the chips are somewhat covered. Add the chocolatechips (with flour) and the toasted walnuts to the batter. Fold in gently. Spread the batter evenly in the prepared pan.
Bake until the top is shiny, cracked and light golden brown, 22-24 minutes. Do not over-bake. Blondies should be chewy, not crunchy.
Cool the Blondies in the pan then lift out using the parchment paper. Transfer to a cutting board and slice into bite sized squares. Enjoy!