Marbled Brownies
["1 c. butter, softened", "1 tsp. vanilla", "2 c. sugar", "4 eggs", "1/2 tsp. salt", "1 3/4 c. flour", "1/4 tsp. baking powder, sifted into flour", "2 c. coarsely chopped nuts", "2 sq. unsweetened chocolate, melted and cooled"]
["Cream butter, vanilla and sugar until light and fluffy.", "Add eggs, one at a time, beating well after each.", "Add flour and salt; mix until well blended.", "Stir in nuts.", "Divide batter in half; add chocolate to one half and mix."]
["butter", "vanilla", "sugar", "eggs", "salt", "flour", "baking powder", "nuts", "unsweetened chocolate"]