- Preheat oven to 375.  Prepare a 9x13 pan by spraying it with non stick cooking spray. 
- In a large bowl, beat together sugar, yogurt, butter and eggs until smooth.  Add in mashed bananas and vanilla and continue to blend.  In a smaller bowl combine flour, baking soda and salt.  Stir dry ingredients into the wet ingredients.  Finally stir in chocolate chips. 
- Spread batter into pan and bake 25-35 minutes, or until a toothpick comes out clean when poked into center. 
- Allow to cool in pan.  Once cake is cooled completely, frost with browned butter chocolate frosting.