Triple-Layer Brownies
["1 (12 oz.) pkg. semi-sweet chocolate pieces", "1 (6 oz.) pkg. butterscotch morsels", "2 c. all-purpose flour", "1 1/2 tsp. baking powder", "1/2 tsp. salt", "1 c. butter", "1 c. brown sugar", "2 tsp. vanilla", "3 eggs", "1 c. chopped walnuts"]
["Preheat oven to 350\u00b0.", "In top part of double boiler, over hot water (not boiling), melt 1 cup chocolate pieces.", "In top part of another double boiler, melt butterscotch morsels."]
["semi-sweet chocolate pieces", "butterscotch morsels", "flour", "baking powder", "salt", "butter", "brown sugar", "vanilla", "eggs", "walnuts"]