Preheat oven to 350F. Line a 9" x 13" , or 7" x 13" pan with parchment paper.
Sift the flour, baking powder and salt and a bowl and set a side.
Melt the butter in a medium-sized saucepan. Add the brown sugar and mix until combined and smooth. Remove from heat and let cool until lukewarm.
Pour the Butter and Sugar mixture into a mixing bowl, mix in the eggs, Vanilla extract, and whiskey. Mix just until combined.
Mix in the flour mixture and mix just to incorporate the flour.
Fold in the Chips and Nuts and spread the mixture evenly in the prepared pan.
Bake until light brown on the sides and top, about 18-20 for 9"x13" or 23-25 minutes for 7" x 11".
Remove the Blondie from the over and let cool completely before slicing.