In a large bowl, combine the flour, sugar, baking powder, baking
soda and salt. In another bowl, combine the egg, oil, yogurt and
vanilla. Stir into dry ingredients just until moistened. Fold in
bananas and chocolate chips. Fill greased or paper lined muffin
cups two thirds full. Bake at 350 degrees for 22-25 minutes or
until a toothpick comes out clean. Cool for 5 minutes before
removing from pans to wire racks.