Cream butter with sugar until blended.
Add eggs, one at a time, beating after each addition.
Mix in mashed banana.
Add flour, baking powder, baking soda, and salt.
Stir in chocolate chips and walnuts.
Spoon into a well-greased 9x5 in loaf pan.
Bake in preheated 350 degree oven 60-70 minutes or until a toothpick inserted in center comes out clean.
Cool for 10 minutes, and enjoy!