Preheat your oven to 350 degrees F and spray a 9x13 baking pan with baking spray.
Grate the zucchini with the skin on. Press the grated zucchini in a fine mesh sieve, extracting the liquid. Discard the liquid and put the squeezed, grated zucchini in a large mixing bowl.
Add the eggs, melted butter, sour cream, oil and vanilla to the zucchini bowl and stir everything together well.
Add the flour, sugar, baking soda, baking powder and cocoa powder to the bowl and stir to make a thick batter.
Spread the batter in the greased pan and bake for 55 minutes. A toothpick inserted into the center of the cake will come out cleanly.
Let the cake cool in the pan while you make the frosting.
Add the chocolate chips to a large mixing bowl. Bring the heavy cream to a boil in a small pot. The moment the cream starts to boil, remove it from the stovetop and pour it into the bowl of chocolate chips.
Let the chocolate chips sit in the heavy cream for one minute then stir, melting the chocolate completely and incorporating it into the heavy cream to make a thick, creamy glaze.
Pour the chocolate ganache into the pan with the zucchini cake, spreading the frosting over the cake evenly.
Place the cake in the fridge to chill for 15 minutes, just to set the ganache and make it sliceable.
Cut and serve the chocolate zucchini cake!
Notes
You can skip the chocolate ganache if you’d like a lighter cake. It's still sweet and delicious without the frosting!