In a large bowl, with an electric mixer on medium speed, beat butter, oil, and brown sugar until smooth. Beat in egg, applesauce, and vanilla until well blended.
In another bowl, mix flour, baking powder, baking soda, and salt; stir or beat into butter mixture until smooth, scraping down sides of bowl as needed. Stir in oats and chocolate chips.
Spread dough evenly in a lightly oiled 8-inch square baking pan. Sprinkle top evenly with granulated sugar.
Bake in a 350° oven until pale golden brown, about 15 minutes. Let cool on a rack about 10 minutes, then cut into 1- by 4-inch bars. Let cool completely.
Note: Nutritional analysis is per bar.