Preheat oven to 180ºC . Cream butter and sugar. Mix inegg and banana. Stir together flour, baking powder,baking soda, salt, nuts and chocolate chips. Add thismixture to creamed mixture alternately withbuttermilk. Stir until just blended. Pour batter intoa greased and floured loaf pan (9x5x3 inches). Bakefor 65 minutes, or until bread tests done. Cool in panfor about 5 minutes, then turn out on a wire rack.