Melt butter in a heavy saucepan. Add sugar. Stir in eggs, flour and baking powder. Add vanilla extract, salt and nuts. Stir in chocolate chips. Pour into a greased 13 x 9-inch pan and bake for 25 minutes.
2(My note: Once the sugar has been mixed in with the melted butter, I prefer to pour it into a mixing bowl and then add the rest of the ingredients. It seems to result in a more brownie-like texture.)