A little mashed banana, and your chocolate chip cookies are twice as sweet.
Turn the oven up to 400 F. While that's heating up, grease the cookie sheets. In a bowl, sift the flour, baking powder, salt, and baking soda together. Set that stuff aside.
In a mixing bowl, cream the butter with the sugar until it's light and fluffy, then beat in the eggs and vanilla. Mix in the mashed bananas, then add the flour mixture, and stir until just combined. Finally, stir in the chocolate chips. Drop spoonfulls of this batter onto the prepped cookie sheets.
Bake the sheets in the preheated oven for 12 to 15 minutes.