Black Bottom Banana Bars
["1/2 c. butter or margarine", "1 c. sugar", "1 egg", "1 tsp. vanilla extract", "1 1/2 c. mashed ripe bananas (about 3 medium)", "1 1/2 c. flour", "1 tsp. baking powder", "1 tsp. baking soda", "1/2 tsp. salt", "1/4 c. baking cocoa"]
["In mixing bowl, cream butter and sugar.", "Add egg and vanilla; beat until thoroughly combined.", "Blend in the bananas.", "Combine the flour, baking powder, baking soda and salt.", "Add to creamed mixture and mix well.", "Divide batter in half.", "Add cocoa to half.", "Spread into a greased 13 x 9-inch baking pan.", "Spoon remaining batter on top and swirl with a knife.", "Bake at 350\u00b0 for 25 minutes, or until the bars test done.", "Cool.", "Yields 2 1/2 to 3 dozen."]
["butter", "sugar", "egg", "vanilla extract", "mashed ripe bananas", "flour", "baking powder", "baking soda", "salt", "baking cocoa"]