In a medium bowl, stir together flour, sugar, baking powder and salt; set aside.
In a large bowl, combine banana, oil, egg and vanilla and mix until well blended. Add the flour mixture, toasted pecans and optional chocolate chips to the banana mixture and stir just until combined. If the mixture seems dry, use your hands to mix until the dough comes together.
Divide the mixture in half and shape each half into an 8 inch log. Place the logs about 4 inches apart on a cookie sheet that has been greased or lined with parchment or Release foil. Press the logs into two rectangles about 3 inches across.
Bake for 30-35 minutes, until firm and cracked on top. Transfer the logs to a wire rack to cool for 15 minutes. Reduce oven temperature to 275 degrees F.
Place logs on a cutting board, trim the ends and using a sharp, serrated knife, cut each diagonally into 1/2 to 3/4 inch thick slices. Place biscotti cut side down on the cookie sheet. Return them to the 275 degree oven and cook for 20 minutes. Flip them over and cook for another 20 minutes . Transfer to a wire rack to cool.
Cookie Madness! Notes: I like to lay a sheet of foil over the biscotti during the second bake. It keeps them from becoming too brown. As for the pecans, I "micro-toast" them. To do this, lay the pecans on a paper towel and heat on high for 2 minutes, stopping to shuffle them around halfway through. Let them cool then chop them up.