Combine flour, baking poder, salt and baking soda. Cream softened butter and sugar until light and fluffy; beat in eggs. Add dry ingredients alternately with mashed bananas just until combined; sir in 1/2 cup chopped peanuts. Scrape batter into well-greased 9" x 5" loaf pan; sprinkle top evenly with remaining chopped peanuts. Bake in 350-degree F. oven 60 to 65 minutes or until toothpick inserted in center comes out clean. Cool in pan on wire rack for 10 minutes; turn out of pan and cool completely. Wrap in plastic wrap or foil. Cake is best if served next day.