Heat oven to 350°F. Grease bottom and sides of 13x9 in. baking pan with shortening. In large bowl, mix granulated sugar, bananas, oil, and eggs. Stir in flour, baking powder, baking soda, cinnamon, and salt. Spread in pan. Bake bars 25-30 minutes or until toothpick comes out clean. Cool completely, about 1 hour.
Cream cheese frosting: Mix cream cheese, butter, and vanilla with electric mixer until blended. Gradually beat in powdered sugar with spoon, until smooth and spreadable. Spread on cooled bars. Store bars covered in refrigerator.