Preheat oven to 325 degrees F (165 degrees C). Grease a 9x13 inch baking pan. Set aside.
In a large mixing bowl, combine butter or margarine and brown sugar; cool slightly. Beat in eggs, one at a time. In a separate bowl, combine flour, baking powder, and salt; add to sugar mixture and mix well. Stir in nuts and chocolate chips.
Pour into prepared pan. Bake for 25 to 30 minutes. When almost cool, cut into 48 squares.
