Preheat oven to 375° degrees F.

In medium bowl stir together flour, baking powder, baking soda and salt.

In large bowl beat butter until light and fluffy. Slowly add brown sugar and then beat additional 2 minutes. Beat in banana, eggs and vanilla, just until combined.

Stir in flour mixture.

Stir in oats, nuts and chocolate chunks.

Drop by heaping teaspoonfuls onto ungreased or parchment paper lined baking sheet.

Bake 8 to 10 minutes or until lightly browned. Cool for one minute before moving to wire rack to cool completely.