Preheat the oven to 350 F. Grease a 9-inch square baking pan with butter or cooking spray and line it with parchment, leaving an overhang, if desired. Grease the parchment paper. If you are not using parchment paper, butter and flour the pan.

Heat the butter in a saucepan over medium heat and cook it, stirring frequently, until it just begins to brown about 2 to 3 minutes. Remove the pan from the heat and set it aside to cool slightly.

Combine the flour, salt, baking powder, and baking soda in a bowl; stir to blend the ingredients thoroughly. Set aside.

In a mixing bowl, combine the brown sugar and butter; whisk until smooth. Whisk in the eggs and vanilla until well blended.

Add the dry ingredients and stir until blended. Fold in the chocolate chips and nuts.

Spread the batter in the prepared pan and bake in the preheated oven for about 25 to 30 minutes, or until browned and a toothpick inserted into the center comes out clean.