In a large mixer combine the sugar, baking powder, baking soda, and salt. Add mashed bananas. Mix in the butter and the milk and beat together for about 2 minutes. Add in the eggs and the flour until well blended. Stir in the nuts if adding them. Pour batter into a greased bread loaf pan. Bake in a 350 degree oven for 55 to 60 minutes or until a toothpick inserted near the center comes out clean. Cool for 10 minutes on a wire rack and then remove from pan and finish cooling on the wire rack.