Preheat the oven to 325 degrees F. Line one 9- by 3-inch cake pan with parchment paper and lightly coat with oil; set aside.
Whisk together the flour, cocoa powder, baking powder, baking soda and salt in a medium bowl. Add the oil, agave nectar and applesauce directly into the dry ingredients. Stir until the batter is smooth.
Pour the batter into the prepared pan. Bake on the center rack until a toothpick inserted in the center comes out clean, 20 minutes.