Begin by grating the zucchini, no peeling necessary! Lay it on a dish towel or paper towels and sprinkle a pinch of salt. 

Let it rest for about 20 minutes to release excess moisture, then give it a good squeeze to remove as much water as possible. Set it aside.

Set your oven to 350°F (175°C) and line a 9x9-inch baking pan with parchment paper to ensure the cake comes out flawlessly and for simple cleanup.

Whisk together the flour, cornstarch, cocoa powder, baking soda, baking powder, espresso powder, and a sprinkle of salt in a big bowl. Mix everything well to combine.

Add the eggs, applesauce, and vanilla extract to the dry ingredients, then carefully incorporate the shredded zucchini. Mix until smooth. The batter should be thick, like brownie batter.

Spoon the batter into the ready pan, making sure it’s leveled out nicely.

Bake for 30 minutes. Test for doneness by inserting a toothpick into the center, if it comes out clean, it's good to go! 

While the cake cools, make the frosting. Heat the butter, then stir in the cocoa powder until smooth and velvety. 

Add the vanilla extract and powdered sugar, then mix in the milk until the frosting is thick, smooth, and spreadable. Tweak the consistency by adding milk to loosen or powdered sugar to firm it up.

Once fully cooled, frost the cake generously with your favorite topping. The rich cake and creamy frosting will come together for the perfect treat. Enjoy!