In small bowl combine flour, baking soda, salt and ground cinnamon.
Cream together butter and sugars; beat until light and fluffy. Add egg, vanilla, banana, and oats. Mix just until combined. Add dry ingredients in three parts mixing and scraping the bowl each time. Stir in chocolate chips.
Drop by rounded tablespoons on to parchment covered cookie sheets. Bake for 16-17 minutes or until the edges are lightly browned. Allow to cool on cookie sheet for 2-3 minutes before moving to wire racks to cool.