Congo Bars
["1 1/2 sticks butter or margarine", "2 c. brown sugar", "2 eggs", "1 tsp. baking powder", "1/4 tsp. baking soda", "1 tsp. salt", "6 oz. chocolate chips", "1/2 c. chopped nuts, (optional)"]
["Melt butter in saucepan over low heat. Remove from heat and add sugar and mix well. Stir in eggs, then sift dry ingredients into mixture. Mix in chocolate chips and nuts. Cook in a greased 13 x 9-inch pan for 30 to 35 minutes at 350\u00b0. Cool in pan and cut when cooled."]
["butter", "brown sugar", "eggs", "baking powder", "baking soda", "salt", "chocolate chips", "nuts"]