Preheat oven to 350 degrees. Combine flour, baking powder and salt in a medium bowl. Beat butter, sugar, brown sugar and vanilla in a large bowl until creamy. Add bananas and egg to butter mixture and beat until combined. Gradually add flour mixture, beating until well combined. Stir in chocolate chips. Spread batter into a greased 9x13 (or 10x15) pan.
Bake for 20-30 minutes or until wooden toothpick inserted in center comes out clean.
If desired, sprinkle with powdered sugar (I put a litte in a sifter and shake it over the cake, just lightly dusting it). Cut into bars. Enjoy!!