Preheat oven to 350 degrees. Grease a 9 inch square pan. In a mixing bowl beat butter until creamy about 1 minute. Stir in Greek yogurt sugar, brown sugar, baking powder and salt. Beat until combined. Add eggs, bananas and vanilla. Stir well. Mix in flour. Mix until thoroughly combined. Stir in chocolate chips.
Spread in greased pan. Bake for about 25 minutes or until a toothpick comes out clean. Cool on wire rack. Cut into about 24 bars.