In a large bowl, combine the flour, sugar, baking powder and salt. Combine the egg, milk, oil, banana and applesauce; stir into dry ingredients just until moistened. Fold in the chocolate chips. Fill greased muffin cups two-thirds full. Bake at 400° for 20 minutes or until a toothpick comes out clean. Cool for 5 minutes before removing from pan to a wire rack.