Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9x13 inch pan.
In a large bowl, mix flour, sugar, baking powder and salt.
In a separate bowl, combine bananas, egg, melted butter and milk.
Stir banana mixture into flour mixture until blended. Be careful not to over mix.
Stir in chocolate chips.
Pour batter into 9x13 inch pan. Bake at 350 degrees F (175 degrees C) 30 to 35 minutes, or until a toothpick inserted into center of cake comes out clean. (It will have some melted chocolate, but no crumbs.)