Preheat the oven to 350 F. Prepare a loaf pan, about 9-inches by lining it with parchment paper and greasing it. Put this aside.
Using a medium-sized bowl, combine the grated zucchini, brown and granulated sugars, eggs, oil and vanilla. Mix well.
Separately, whisk the dry ingredients together : the flour, cocoa powder, salt, baking soda and baking powder.
Add the zucchini mixture to the dry ingredients. Blend well either by hand or using a stand mixer.
Stir by hand the chocolate chips into the batter. Pour the batter into the loaf pan.
Bake 45 to 50 minutes at 350 F. Test for doneness by piercing the tip of a sharp, thin knife in the center. If knife comes clean, chocolate loaf is done. Allow the chocolate loaf to cool on the counter for a few minutes. Then invert on a wire rack to cool completely.
To serve, slice the chocolate loaf and serve warm or at room temperature.