In large mixing bowl, cream 1/2 cup butter, applesauce, white sugar, and 1 3/4 cup powdered sugar. Add eggs one at a time, mixing well after each addition. Add vanilla and mix to incorporate. In a separate bowl, mix flour and cocoa together. Add the egg mixture and mix well to combine. Add granola and mix to combine. Pour into prepared pan and bake for 40 minutes. While still how, cover cake with mini marshmallows. Let cool. To make frosting: in small bowl combine 4 Tbsp.