Mash bananas with a fork in a small mixing bowl and set to the side. In a large mixing bowl, cream together butter and sugars. Add bananas, mix. Add eggs and vanilla, mix until smooth. Gently stir in the flour and baking powder. Do not over mix or it will make the bread tough. Fold in optional chocolate chunks and nuts. Spoon batter into the prepared pan. Bake for 1 hour and 10 minutes or until lightly golden brown around the edges.
Tip: A plain toothpick should be able to come out clean when inserted into the center of the banana bread.