Preheat the oven to 350°F (175°C). Grease a baking pan.

In a mixing bowl, whisk together the applesauce, vegetable oil, and brown sugar until smooth.

Add the eggs one at a time, mixing well after each addition.

In another bowl, combine the flour, cocoa powder, baking powder, and salt.

Gradually add the dry ingredients to the wet mixture, stirring until just combined.

Fold in the chopped apples and chocolate chips if using.

Pour the batter into the prepared baking pan and spread evenly.

Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted in the center comes out clean.

Allow to cool in the pan for 10 minutes before transferring to a wire rack to cool completely.