Preheat the oven to 350°F (175°C). Grease and flour a 9x13 inch baking pan.

In a mixing bowl, whisk together the dry ingredients: flour, sugar, cocoa powder, baking soda, baking powder, and salt.

In another bowl, mix the wet ingredients: vegetable oil, eggs, and vanilla extract until well combined.

Add the grated zucchini to the wet mixture and stir until combined.

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

Fold in the chocolate chips if using.

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

Bake in the preheated oven for 30-35 minutes, or until a toothpick inserted in the center comes out clean.

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

Dust with powdered sugar before serving, if desired.